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Sample records for susceptibility collapses indicating

  1. Evaluating susceptibility of karst dolines (sinkholes) for collapse in Sango, Tennessee, USA

    Science.gov (United States)

    Siska, Peter P.; Goovaerts, Pierre; Hung, I-K

    2016-01-01

    Dolines or sinkholes are earth depressions that develop in soluble rocks complexes such as limestone, dolomite, gypsum, anhydrite, and halite; dolines appear in a variety of shapes from nearly circular to complex structures with highly curved perimeters. The occurrence of dolines in the studied karst area is not random; they are the results of geomorphic, hydrologic, and chemical processes that have caused partial subsidence, even the total collapse of the land surface when voids and caves are present in the bedrock and the regolith arch overbridging these voids is unstable. In the study area, the majority of collapses occur in the regolith (bedrock cover) that bridges voids in the bedrock. Because these collapsing dolines may result in property damage and even cause the loss of lives, there is a need to develop methods for evaluating karst hazards. These methods can then be used by planners and practitioners for urban and economic development, especially in regions with a growing population. The purpose of this project is threefold: 1) to develop a karst feature database, 2) to investigate critical indicators associated with doline collapse, and 3) to develop a doline susceptibility model for potential doline collapse based on external morphometric data. The study has revealed the presence of short range spatial dependence in the distribution of the dolines’ morphometric parameters such as circularity, the geographic orientation of the main doline axes, and the length-to-width doline ratios; therefore, geostatistics can be used to spatially evaluate the susceptibility of the karst area for doline collapse. The partial susceptibility estimates were combined into a final probability map enabling the identification of areas where, until now, undetected dolines may cause significant hazards. PMID:27616807

  2. Evaluating susceptibility of karst dolines (sinkholes) for collapse in Sango, Tennessee, USA.

    Science.gov (United States)

    Siska, Peter P; Goovaerts, Pierre; Hung, I-K

    2016-08-01

    Dolines or sinkholes are earth depressions that develop in soluble rocks complexes such as limestone, dolomite, gypsum, anhydrite, and halite; dolines appear in a variety of shapes from nearly circular to complex structures with highly curved perimeters. The occurrence of dolines in the studied karst area is not random; they are the results of geomorphic, hydrologic, and chemical processes that have caused partial subsidence, even the total collapse of the land surface when voids and caves are present in the bedrock and the regolith arch overbridging these voids is unstable. In the study area, the majority of collapses occur in the regolith (bedrock cover) that bridges voids in the bedrock. Because these collapsing dolines may result in property damage and even cause the loss of lives, there is a need to develop methods for evaluating karst hazards. These methods can then be used by planners and practitioners for urban and economic development, especially in regions with a growing population. The purpose of this project is threefold: 1) to develop a karst feature database, 2) to investigate critical indicators associated with doline collapse, and 3) to develop a doline susceptibility model for potential doline collapse based on external morphometric data. The study has revealed the presence of short range spatial dependence in the distribution of the dolines' morphometric parameters such as circularity, the geographic orientation of the main doline axes, and the length-to-width doline ratios; therefore, geostatistics can be used to spatially evaluate the susceptibility of the karst area for doline collapse. The partial susceptibility estimates were combined into a final probability map enabling the identification of areas where, until now, undetected dolines may cause significant hazards.

  3. Progressive collapse susceptibility of a long span suspension bridge

    DEFF Research Database (Denmark)

    Olmati, Pierluigi; Giuliani, Luisa

    2013-01-01

    should be maintained in case of an accidental hanger detachment. Local damages in bridges, which are characterized by an horizontal load transfer system, may progress along the deck or along the suspension system, as the dynamic overloading of the structural elements immediately adjacent to the failed...... ones may lead to subsequent failures. In suspension bridges, which are characterized by a relatively low continuity of the system, the damage of the deck may favor a collapse standstill, in case of an early detachment of the deck collapsing section. In the paper, a long span suspension bridge is taken...

  4. Karst collapse susceptibility assessment: A case study on the Amalfi Coast (Southern Italy)

    Science.gov (United States)

    Santo, Antonio; Budetta, Paolo; Forte, Giovanni; Marino, Ermanno; Pignalosa, Antonio

    2017-05-01

    This paper presents a study to evaluate the collapse susceptibility of a karst cave located along a slope on the Amalfi coast (southern Italy) and the presumable geomorphological evolution of the whole slope as a result of cave roof collapse. In the study area, several natural karst caves with volumes varying between 1000 and > 10,000 m3 were inventoried and the most likely genetic processes were identified. Some of them proved to be remnants of already collapsed caves, while others were in precarious stability conditions. The caves are usually located upslope or very close to the main populated resorts. A detailed geological, geomorphological and geostructural study was performed on a very wide, deep cave (called the "Saraceno" cave), on which the resort town of Conca de' Marini has been built. The study was carried out through a multidisciplinary approach, which included classical field geological observations, sometimes requiring the support of rock-climbing geologists, experts in photogrammetric surveys and terrestrial laser scanning techniques (TLS). TLS surveys allowed the reconstruction of an accurate geometric and geostructural model of the cave and its relationship with the upslope Conca de' Marini resort. Furthermore, it allowed the thickness of the cave overburden to be determined in detail; ground surfaces most susceptible to collapse were also identified. In the event of possible widespread collapse, several buildings and transportation infrastructures could be involved. As the cave is located on a very steep slope, a debris avalanche could be triggered in the event of a catastrophic failure, and the landslide debris, characterized by a presumably high magnitude and velocity, could involve a wide slope area down to the coast. The failure evolution could be very similar to that which took place in Amalfi in the late 19th century.

  5. Is the Housing Bubble Collapsing? 10 Economic Indicators to Watch

    OpenAIRE

    Dean Baker

    2006-01-01

    This report describes the key economic indicators that indicate the state of the housing market. It gives up-to-date analysis of the available data sources, such as home sales, mortgage applications, vacancy rates and construction.

  6. Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation.

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

    2016-04-15

    We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse.

  7. Micro kinematic indicators in the Green Tuff Ignimbrite: can they tell us about caldera collapse?

    OpenAIRE

    Williams, Rebecca; Dyble, Jodie

    2014-01-01

    This poster presents the results from a 4 week research placement through the Nuffield Foundation scheme. Jodie created this poster as part of the assessment for a Gold CREST Award from the British Science Association. We are also presenting this poster at the VMSG conference, Norwich, 2015. It should be cited as: Dyble, J.A., Williams, R., 2015. Micro kinematic indicators in the Green Tuff Ignimbrite: can they tell us about caldera collapse? VMSG Meeting, Norwch, 5th-7th January 2015. htt...

  8. Hippopotamus (H. amphibius) diet change indicates herbaceous plant encroachment following megaherbivore population collapse.

    Science.gov (United States)

    Chritz, Kendra L; Blumenthal, Scott A; Cerling, Thure E; Klingel, Hans

    2016-09-12

    Megaherbivores (>1000 kg) are critical for ecosystem health and function, but face population collapse and extinction globally. The future of these megaherbivore-impoverished ecosystems is difficult to predict, though many studies have demonstrated increasing representation of C3 woody plants. These studies rely on direct observational data, however, and tools for assessing decadal-scale changes in African ecology without observation are lacking. We use isotopic records of historical common hippopotamus (Hippopotamus amphibius) canines to quantify herbaceous vegetation change in Queen Elizabeth National Park, Uganda following a period of civil unrest and poaching. This poaching event led to population collapse of two threatened African megaherbivore species: hippopotamus and African elephants (Loxodonta africana). Serial carbon isotope ratios (δ(13)C) in canine enamel from individuals that lived between 1960-2000 indicated substantial increases in C3 herbaceous plants in their diet (<20% C3 in the 1960s to 30-45% C3 in the 80s and 90s), supported by other observational and ecological data. These data indicate megaherbivore loss results in succession of both woody and herbaceous C3 vegetation and further reaching effects, such as decreased grazing capacity and herbivore biodiversity in the area. Given multiple lines of evidence, these individuals appear to accurately capture herbaceous vegetation change in Mweya.

  9. Using the cavitation collapse time to indicate the extent of histotripsy-induced tissue fractionation.

    Science.gov (United States)

    Macoskey, Jonathan Jenner; Choi, Sang Won; Hall, Timothy L; Vlaisavljevich, Eli; Lundt, Jonathan Erik; Lee, Fred T; Johnsen, Eric; Cain, Charles A; Xu, Zhen

    2018-02-09

    Histotripsy is an ultrasonic tissue ablation method based on acoustic cavitation. It has been shown that cavitation dynamics change depending on the mechanical properties of the host medium. During histotripsy treatment, the target-tissue is gradually fractionated and eventually liquefied to acellular homogenate. In this study, the change in the collapse time (tcol) of the cavitation bubble cloud over the course of histotripsy treatment is investigated as an indicator for progression of the tissue fractionation process throughout treatment. A 500-kHz histotripsy transducer is used to generate single-location lesions within tissue-mimicking agar phantoms of varying stiffness levels as well as ex vivo bovine liver samples. Cavitation collapse signals are acquired with broadband hydrophones, and cavitation is imaged optically using a high-speed camera in transparent tissue-mimicking phantoms. The high-speed-camera-acquired measurements of tcol validate the acoustic hydrophone measurements. Increases in tcol are observed both with decreasing phantom stiffness and throughout histotripsy treatment with increasing number of pulses applied. The increasing trend of tcol throughout the histotripsy treatment correlates well with the progression of lesion formation generated in tissue-mimicking phantoms (R2 = 0.87). Finally, the increasing trend of tcol over the histotripsy treatment is validated in ex vivo bovine liver. © 2018 Institute of Physics and Engineering in Medicine.

  10. The Usability of a Pressure-Indicating Film to Measure the Teat Load Caused by a Collapsing Liner

    Directory of Open Access Journals (Sweden)

    Susanne Demba

    2016-09-01

    Full Text Available Prevention of damage to the teat and mastitis requires determination of the teat load caused by a collapsing liner. The aim of this study was to test a pressure-indicating film designed to measure the pressure between a collapsing liner and artificial teats. The Ultra Super Low and the Extreme Low pressure-indicating films were tested on two types of artificial teat. The experiments were performed with a conventional milking cluster equipped with round silicone liners. For each teat and film type, 30 repetitions were performed. Each repetition was performed with a new piece of film. Kruskal-Wallis tests were performed to detect differences between the pressure values for the different teats. The area of regions where pressure-indication color developed was calculated to determine the most suitable film type. Both film types measured the pressure applied to both artificial teats by the teat cup liner. Thus, the pressure-indicating films can be used to measure the pressure between a collapsing liner and an artificial teat. Based on the results of the present investigation, a pressure-indicating film with the measurement ranges of both film types combined would be an optimal tool to measure the overall pressure between an artificial teat and a collapsing liner.

  11. Red Blood Cell Parameters as Indices of Susceptibility to ...

    African Journals Online (AJOL)

    The anaemia recorded in infected cattle by 38 days post-infection (pi) was mildest in WF and most severe in SG. It was concluded that low red blood cell values (PCV, Hb and RBC) are some of the markers that are consistently associated with susceptibility of cattle to trypanosomosis. Of the three cattle breeds studied, the ...

  12. Maturation trends indicative of rapid evolution preceded the collapse of northern cod.

    Science.gov (United States)

    Olsen, Esben M; Heino, Mikko; Lilly, George R; Morgan, M Joanne; Brattey, John; Ernande, Bruno; Dieckmann, Ulf

    2004-04-29

    Northern cod, comprising populations of Atlantic cod (Gadus morhua) off southern Labrador and eastern Newfoundland, supported major fisheries for hundreds of years. But in the late 1980s and early 1990s, northern cod underwent one of the worst collapses in the history of fisheries. The Canadian government closed the directed fishing for northern cod in July 1992, but even after a decade-long offshore moratorium, population sizes remain historically low. Here we show that, up until the moratorium, the life history of northern cod continually shifted towards maturation at earlier ages and smaller sizes. Because confounding effects of mortality changes and growth-mediated phenotypic plasticity are accounted for in our analyses, this finding strongly suggests fisheries-induced evolution of maturation patterns in the direction predicted by theory. We propose that fisheries managers could use the method described here as a tool to provide warning signals about changes in life history before more overt evidence of population decline becomes manifest.

  13. Assessing MRI susceptibility artefact through an indicator of image distortion

    Directory of Open Access Journals (Sweden)

    Illanes Alfredo

    2016-09-01

    Full Text Available Susceptibility artefacts in magnetic resonance imaging (MRI caused by medical devices can result in a severe degradation of the MR image quality. The quantification of susceptibility artefacts is regulated by the ASTM standard which defines a manual method to assess the size of an artefact. This means that the estimated artefact size can be user dependent. To cope with this problem, we propose an algorithm to automatically quantify the size of such susceptibility artefacts. The algorithm is based on the analysis of a 3D surface generated from the 2D MR images. The results obtained by the automatic algorithm were compared to the manual measurements performed by study participants. The results show that the automatic and manual measurements follow the same trend. The clear advantage of the automated algorithm is the absence of the inter- and intra-observer variability. In addition, the algorithm also detects the slice containing the largest artefact which was not the case for the manual measurements.

  14. Foundation Considerations in Siting of Nuclear Facilities in Karst Terrains and Other Areas Susceptible to Ground Collapse.

    Science.gov (United States)

    1981-05-01

    outlet (if present) at the base of a sinkhole or a conduit leading downward is called a swallow hole or ponor. Sinkholes that are partially filled with...Figure 2.1 is a topo- graphic map showing a sink-dominated landscape in Kentucky. Collapse sinks are often filled with coarse, angular rock fragments...Such features may on occasion be mistaken for kettles . Differential solution may produce groove-, furrow-, or channel- shaped depressions on

  15. Collapse of axion stars

    Energy Technology Data Exchange (ETDEWEB)

    Eby, Joshua [Department of Physics, University of Cincinnati,2600 Clifton Ave, Cincinnati, OH, 45221 (United States); Fermi National Accelerator Laboratory,P.O. Box 500, Batavia, IL, 60510 (United States); Leembruggen, Madelyn; Suranyi, Peter; Wijewardhana, L.C.R. [Department of Physics, University of Cincinnati,2600 Clifton Ave, Cincinnati, OH, 45221 (United States)

    2016-12-15

    Axion stars, gravitationally bound states of low-energy axion particles, have a maximum mass allowed by gravitational stability. Weakly bound states obtaining this maximum mass have sufficiently large radii such that they are dilute, and as a result, they are well described by a leading-order expansion of the axion potential. Heavier states are susceptible to gravitational collapse. Inclusion of higher-order interactions, present in the full potential, can give qualitatively different results in the analysis of collapsing heavy states, as compared to the leading-order expansion. In this work, we find that collapsing axion stars are stabilized by repulsive interactions present in the full potential, providing evidence that such objects do not form black holes. In the last moments of collapse, the binding energy of the axion star grows rapidly, and we provide evidence that a large amount of its energy is lost through rapid emission of relativistic axions.

  16. Preliminary indications for antibiotic susceptibility tests in less than six hour in positive blood cultures

    Directory of Open Access Journals (Sweden)

    Vesselina Kroumova

    2010-03-01

    Full Text Available A rapid determination of the antibiotic susceptibility patterns of pathogens responsible for sepsis represents a significant milestone for a timely correct antibiotic therapy.The system HB&L® (ALIFAX allows reduced time in the detection of bacterial growth and consequently is able to detect the growth or absence of certain microorganisms in the presence of a given antibiotic. In this study three system for rapid antibiotic susceptibility tests among bacteria isolated from blood were compared: HB&L® (ALIFAX,VITEK®2 (bioMérieux and essays Etest® (bioMérieux. Present findings indicate that HB&L® (ALIFAX is rapid reliable instrument that may support the clinician for a rapid and appropriate treatment, particularly in the critical patient.

  17. The Use of a Pressure-Indicating Film to Determine the Effect of Liner Type on the Measured Teat Load Caused by a Collapsing Liner

    Science.gov (United States)

    Demba, Susanne; Paul, Viktoria; Ammon, Christian; Rose-Meierhöfer, Sandra

    2017-01-01

    During milking the teat cup liner is the interface between the teat of a dairy cow and the milking system, so it should be very well adapted to the teat. Therefore, the aim of the present study was to determine the effect of liner type on the directly measuring teat load caused by a collapsing liner with a pressure-indicating film. The Extreme Low pressure-indicating film was used to detect the effect of six different liners on teat load. For each liner, six positions in the teat cup were specified, and six repetitions were performed for each position with a new piece of film each time. Analysis of variance was performed to detect differences between the six liners, the positions within a liner, and the measuring areas. The pressure applied to the teat by a liner depends on the technical characteristics of the liner, especially the shape of the barrel, and for all tested liners, a higher teat load was found at the teat end. In conclusion, with the help of pressure-indicating film, it is possible to determine the different effects of liner type by directly measuring teat load due to liner collapse. PMID:28406465

  18. Collapsing Containers.

    Science.gov (United States)

    Brown, Justina L.; Battino, Rubin

    1994-01-01

    Describes variations on atmospheric pressure demonstrations and some systematic studies. Demonstrations use steam, generated either externally or internally to the container, to sweep out residual air. Preferred vessels collapsed slowly. Demonstrations use plastic milk jugs set in layers of aluminum foil, pop bottles immersed in 4-L beakers…

  19. Identification and behavior of collapsible soils : [technical summary].

    Science.gov (United States)

    2011-01-01

    Collapsible soils are susceptible to large volumetric strains when they become saturated. Numerous soil types : fall in the general category of collapsible soils, including : loess, a well-known aeolian deposit, present throughout : most of Indiana. ...

  20. Evaluation of indicators to determine black sigatoka susceptibility in five banana hybrid cultivars ( Mycosphaerella fijiensis Morelet

    Directory of Open Access Journals (Sweden)

    Reinaldo Pérez Armas

    2014-10-01

    Full Text Available This work had the objective of determining the variation of growth, development and yields indicators of five banana hybrid cultivars. The research was carried in the Agroindustrial Farm Marta Abreu, Cienfuegos, in a carbonated Brown soil. It was made a characterization of the soil and the climatic variables. A field experiment was developed with a design in blocks at random with four repetitions with five banana cultivars as treatments (‘FHIA-18’, ‘FHIA-02’, ‘FHIA-01’, ‘SH-3436 L-9’ and ‘FHIA-23’ . The plots had an area of 56 m2 with 16 plants, been evaluated eight for a total 32 plants for cultivar. The variable evaluated were the spotty youngest leaf, number of leaf by plant, incubation time (PI, evolution time of symptoms (TES and developing time of symptoms (TED, severity index (IS, active photosynthetic index (INHE and infection relative index. The cultivars FHIA-23 and SH 3436 L9 presented a hither time of development of the disease. In a general the more susceptible cultivar to the black Sigatoka under of the farm condition was FHIA-23. The clones FHIA-18, FHIA-01 and FHIA-02 presented the best behavior in the spotted youngest leaf and the number of leaf up to the flowering and the harvest time. The clones FHIA-01 and FHIA-18 have the better response to Black Sigatoka attending to the incubation period, the evolution time of the symptom and develo pment time of the disease

  1. Collapsed City

    DEFF Research Database (Denmark)

    Allen, Nacho Ruiz

    2015-01-01

    Currently, when the socio-economic circumstances seem to announce another change of cultural paradigm for the 21st century, the interest in the urban fact seems to have been renewed in architecture. However, this is no longer focused on models of growth and efficiency, as happened in the 70s...... with its imminent breakdown, the architectural interests have shifted to urban environments like Tokyo, Detroit, Lagos or Rio de Janeiro; places that demonstrate, somehow, an urban culture of collapse....

  2. Multicenter evaluation of fully automated BACTEC Mycobacteria Growth Indicator Tube 960 system for susceptibility testing of Mycobacterium tuberculosis.

    Science.gov (United States)

    Bemer, Pascale; Palicova, Frantiska; Rüsch-Gerdes, Sabine; Drugeon, Henri B; Pfyffer, Gaby E

    2002-01-01

    The reliability of the BACTEC Mycobacteria Growth Indicator Tube (MGIT) 960 system for testing of Mycobacterium tuberculosis susceptibility to the three front-line drugs (isoniazid [INH], rifampin [RIF], and ethambutol [EMB]) plus streptomycin (STR) was compared to that of the BACTEC 460 TB system. The proportion method was used to resolve discrepant results by an independent arbiter. One hundred and ten strains were tested with an overall agreement of 93.5%. Discrepant results were obtained for seven strains (6.4%) with INH (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for one strain (0.9%) with RIF (resistant by BACTEC MGIT 960; susceptible by BACTEC 460 TB), for seven strains (6.4%) with EMB (six resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB; one susceptible by BACTEC MGIT 960 and resistant by BACTEC 460 TB), and for 19 strains (17.3%) with STR (resistant by BACTEC MGIT 960 and susceptible by BACTEC 460 TB). After resolution of discrepant results, the sensitivity of the BACTEC MGIT 960 system was 100% for all four drugs and specificity ranged from 89.8% for STR to 100% for RIF. Turnaround times were 4.6 to 11.7 days (median, 6.5 days) for BACTEC MGIT 960 and 4.0 to 10.0 days (median, 7.0 days) for BACTEC 460 TB. These data demonstrate that the fully automated and nonradiometric BACTEC MGIT 960 system is an accurate method for rapid susceptibility testing of M. tuberculosis.

  3. Prioritising watersheds on the basis of regional flood susceptibility and vulnerability in mountainous areas through the use of indicators

    Science.gov (United States)

    Rogelis, Carolina; Werner, Micha

    2013-04-01

    Settlements in peri-urban areas of many cities in mountainous areas such as in the Andes are susceptible to hazards such as flash floods and debris flows. Additionally these settlements are in many cases informal and thus vulnerable to such hazards, resulting in significant risk. Such watersheds are often quiet small, and generally there is little or no information from gauges to help characterise risk. To help identify watersheds in which flood management measures are to be targeted, a rapid assessment of risk is required. In this paper a novel approach is presented where indicators of susceptibility and vulnerability to flash floods were used to prioritize 106 mountain watersheds in Bogotá (Colombia). Variables recognized in literature to determine the dominant processes both in susceptibility and vulnerability to flash floods were used to construct the indicators. Susceptibility was considered to increase with flashiness and the possibility of debris flow events occurring. This was assessed through the use of an indicator composed of a morphometric indicator and a land use indicator. The former was constructed using morphological variables recognized in literature to significantly influence flashiness and occurrence of debris flows; the latter was constructed in terms of percentage of vegetation cover, urban area and bare soil. The morphometric indicator was compared with the results of a debris flow propagation algorithm to assess its capacity in indentifying the morphological conditions of a watershed that make it able to transport debris flows. Propagation was carried out through the use of the Modified Single Flow Direction algorithm, following previous identification of source areas by applying thresholds identified in the area-slope curve of the watersheds and empirical thresholds. Results show that the morphometric variables can be grouped in four categories: size, shape, hypsometry and energy, with the energy the component found to best explain the

  4. Rock fall susceptibility assessment using structural geological indicators for detaching processes such as sliding or toppling

    Science.gov (United States)

    Melzner, Sandra; Tilch, Nils; Lotter, Michael; Kociu, Arben

    2010-05-01

    A structural geological assessment of cliffs in terms of rock fall susceptibility is expensive and time-consuming particularly in remote areas (exposed cliffs) where it may even be impossible. Hence it is important to develop methods and strategies that can be used to extrapolate the acquired knowledge from representative sub-regions to the whole study area. Using a case study in Carinthia (Austria), a GIS method was developed which can be used for regional, qualitative determination of the susceptibility of cliffs in carbonatic sedimentary rock, regarding two potential initial detachment processes of rock fall: sliding and/or toppling. During the development of this GIS method, it was found that not all of the mapped structural geologic parameters are equally suitable for a comprehensive regionalisation. Subsequently, only those parameters were included in the assessment which experts deemed to be representative in terms of parameter homogeneity/heterogeneity and thus applicable to the entire survey region: bedding thickness, tectonic lineaments, orientation of discontinuities and type of rock mass structure. Regions of homogeneity/heterogeneity differ with regard to parameter values, as well as parameter uncertainties and scattering. At first, the cliffs were categorised in terms of potential form and size of rock blocks by overlaying various parameter maps. In the next step, the relative orientation of the rock mass structures and their variations towards slope aspect and slope inclination were considered within a region of homogeneity. This allowed an accurate estimate of the possible maximum dip angle (or apparent dip angle) of a joint set over a wide area. It also permitted those areas to be pointed out in which process-initialising sliding and/or toppling might be possible along one or several joint sets. Comparing this method to the acquired field data has proven the approach to be successful when it comes to assessing cliffs in carbonate rocks in terms of

  5. Comparison of manual mycobacteria growth indicator tube and epsilometer test with agar proportion method for susceptibility testing of Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    N Karabulut

    2014-01-01

    Full Text Available Background and Objectives: Antimycobacterial susceptibility tests take weeks, and delayed therapy can lead to spread of Mycobacterium tuberculosis. Therefore, rapid, accurate and cost-effective methods are required for proper therapy selection. In this study, the Mycobacteria growth indicator tube (MGIT and epsilometer test (Etest methods were compared to the agar proportion method for susceptibility testing of Mycobacterium tuberculosis. Materials and Methods: The susceptibility tests against isoniazid (INH, rifampin (RIF, streptomycin (STM and ethambutol (ETM of 51 M. tuberculosis complex isolates were analyzed by the MGIT, Etest and agar proportion methods. Results: The concordance between MGIT/Etest and agar proportion methods was 98% for INH and 100% for RIF, STM, ETM. There were not statistically significant differences in results of the susceptibility tests between MGIT/Etest and the reference agar proportion method. Conclusion: The results have shown that MGIT and Etest methods can be used instead of the agar proportion method, because these two methods are more rapid and easier than the agar proportion method.

  6. Fatty acid composition of the anterior cingulate cortex indicates a high susceptibility to lipid peroxidation in Parkinson's disease.

    Science.gov (United States)

    Abbott, Sarah K; Jenner, Andrew M; Spiro, Adena S; Batterham, Marijka; Halliday, Glenda M; Garner, Brett

    2015-01-01

    Oxidative stress contributes to Parkinson's disease (PD) etiology. Although previous studies have focused on sources of free radical formation in brain regions affected by PD, less is known regarding changes in lipid composition and the implications for susceptibility to peroxidation. To assess fatty acid profiles from control and PD tissues that are susceptible to PD pathology but devoid of severe destruction. We used gas chromatography methods to assess fatty acid profiles from control (n = 10) and PD (n = 9) postmortem tissues. We focused on the anterior cingulate cortex (ACC), a region that accumulates alpha-synuclein, but does not undergo severe destruction, and compared this to the occipital cortex, a region that is pathologically spared. Our data indicate a significant 33% increase in the proportion of polyunsaturated fatty acids (mol%) present in the PD ACC as compared to control ACC. Increases in highly unsaturated 22:5n-6 and 22:6n-3 fatty acids were particularly pronounced (109% and 73%, respectively). Calculation of a peroxidation index (accounting for total fatty acyl double bounds) indicated a 44% increase in susceptibility of the PD ACC to lipid peroxidation compared to control ACC. Such differences were not detected in the occipital cortex from the same donors. Assessment of F2-isprostane levels confirmed that PD tissue lipids were more oxidized than controls. The global composition of fatty acids in the PD ACC is altered in a way that increases susceptibility to peroxidation in a region-specific manner. This has important implications for PD, supporting the oxidative stress hypothesis of PD pathogenesis.

  7. Integrative analyses of leprosy susceptibility genes indicate a common autoimmune profile.

    Science.gov (United States)

    Zhang, Deng-Feng; Wang, Dong; Li, Yu-Ye; Yao, Yong-Gang

    2016-04-01

    Leprosy is an ancient chronic infection in the skin and peripheral nerves caused by Mycobacterium leprae. The development of leprosy depends on genetic background and the immune status of the host. However, there is no systematic view focusing on the biological pathways, interaction networks and overall expression pattern of leprosy-related immune and genetic factors. To identify the hub genes in the center of leprosy genetic network and to provide an insight into immune and genetic factors contributing to leprosy. We retrieved all reported leprosy-related genes and performed integrative analyses covering gene expression profiling, pathway analysis, protein-protein interaction network, and evolutionary analyses. A list of 123 differentially expressed leprosy related genes, which were enriched in activation and regulation of immune response, was obtained in our analyses. Cross-disorder analysis showed that the list of leprosy susceptibility genes was largely shared by typical autoimmune diseases such as lupus erythematosus and arthritis, suggesting that similar pathways might be affected in leprosy and autoimmune diseases. Protein-protein interaction (PPI) and positive selection analyses revealed a co-evolution network of leprosy risk genes. Our analyses showed that leprosy associated genes constituted a co-evolution network and might undergo positive selection driven by M. leprae. We suggested that leprosy may be a kind of autoimmune disease and the development of leprosy is a matter of defect or over-activation of body immunity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  8. Geotechnical properties of Egyptian collapsible soils

    Directory of Open Access Journals (Sweden)

    Khaled E. Gaaver

    2012-09-01

    Full Text Available The risk of constructing structures on collapsible soils presents significant challenges to geotechnical engineers due to sudden reduction in volume upon wetting. Identifying collapsible soils when encountered in the field and taking the needed precautions should substantially reduce the risk of such problems usually reported in buildings and highways. Collapsible soils are those unsaturated soils that can withstand relatively high pressure without showing significant change in volume, however upon wetting; they are susceptible to a large and sudden reduction in volume. Collapsible soils cover significant areas around the world. In Egypt, collapsible soils were observed within the northern portion of the western desert including Borg El-Arab region, and around the city of Cairo in Six-of-October plateau, and Tenth-of-Ramadan city. Settlements associated with development on untreated collapsible soils usually lead to expensive repairs. One method for treating collapsible soils is to densify their structure by compaction. The ongoing study presents the effect of compaction on the geotechnical properties of the collapsible soils. Undisturbed block samples were recovered from test pits at four sites in Borg El-Arab district, located at about 20 km west of the city of Alexandria, Egypt. The samples were tested in both unsoaked and soaked conditions. Influence of water inundation on the geotechnical properties of collapsible soils was demonstrated. A comparative study between natural undisturbed and compacted samples of collapsible soils was performed. An attempt was made to relate the collapse potential to the initial moisture content. An empirical correlation between California Bearing Ratio of the compacted collapsible soils and liquid limit was adopted. The presented simple relationships should enable the geotechnical engineers to estimate the complex parameters of collapsible soils using simple laboratory tests with a reasonable accuracy.

  9. Screening for Terminal Drought Tolerance in Iranian and Exotic Safflower Genotypes Using Drought Tolerance and Susceptibility Indices

    Directory of Open Access Journals (Sweden)

    R. Maleki Nejad

    2015-06-01

    Full Text Available This research was conducted to evaluate drought tolerance of safflower genotypes (Carthamus tinctorius L. at the research farm of Isfahan University of Technology, Isfahan, Iran during growing season of 2012. One hundred genotypes including 81 foreign genotypes along with 19 Iranian genotypes were evaluated under normal and moisture stress conditions according to a simple lattice design with two replications. Drought tolerance and sensitivity indices including mean productivity (MP, geometric mean productivity (GMP, stress tolerance index (STI, tolerance (TOL and stress susceptibility index (SSI were studied. Results of this study indicated that genotypes were significantly different for grain yield in both moisture conditions. Among all indices, MP, GMP and STI were identified as the best indices that can be used to determine tolerant genotypes. Based on MP, GMP and STI and also principal component analysis PI 369847 (Tajikistan, CART 56 (USA, PI 657820 (Jordan, PI 305527 (Soudan were determined as the most tolerant genotypes and PI 537652 (Mexico, CART 131 (Prague, PI 470942 (Bangladesh, PI 209286 (Romania and CART 32 (German as the most sensitive ones. Results also indicated that the biplot of principal component analysis is a powerful technique to discriminate genotypes based on the measured indices. The superior safflower genotypes can be used in future breeding programs.

  10. Kax and kol: collapse and resilience in lowland Maya civilization.

    Science.gov (United States)

    Dunning, Nicholas P; Beach, Timothy P; Luzzadder-Beach, Sheryl

    2012-03-06

    Episodes of population loss and cultural change, including the famous Classic Collapse, punctuated the long course of Maya civilization. In many cases, these downturns in the fortunes of individual sites and entire regions included significant environmental components such as droughts or anthropogenic environmental degradation. Some afflicted areas remained depopulated for long periods, whereas others recovered more quickly. We examine the dynamics of growth and decline in several areas in the Maya Lowlands in terms of both environmental and cultural resilience and with a focus on downturns that occurred in the Terminal Preclassic (second century Common Era) and Terminal Classic (9th and 10th centuries CE) periods. This examination of available data indicates that the elevated interior areas of the Yucatán Peninsula were more susceptible to system collapse and less suitable for resilient recovery than adjacent lower-lying areas.

  11. Use of Aeromonas spp. as general indicators of antimicrobial susceptibility among bacteria in aquatic environments in Thailand

    Directory of Open Access Journals (Sweden)

    Masaru eUsui

    2016-05-01

    Full Text Available Antimicrobials are widely used, not only for treating human infections, but also for treatment of livestock and in fish farms. Human habitats in Southeastern Asian countries are located in close proximity to aquatic environments. As such, the human populations within these regions are at risk of exposure to antimicrobial resistant bacteria (ARB, and thereby disseminating antimicrobial resistance genes (ARGs. In this study, we collected water samples from 15 sites (5 sites in Chao Phraya River, 2 sites at the mouth of Chao Phraya River, 3 sites in Ta Chin River, and 5 sites at city canals and 12 sites (6 sites at city canals, 2 sites at chicken farms, 2 sites at pig farms, and 2 samples from sites at pig farms that were subsequently treated at a biogas plant in Thailand in 2013 and 2014, respectively. In total, 117 Aeromonas spp. were isolated from the water samples, and these organisms exhibited various antimicrobial susceptibility profiles. Moreover, there was a significant correlation between the environmental concentration of tetracyclines and the rates of tetracycline resistance in the isolated Aeromonas spp. Notably, however, the concentration and resistance rates of tetracycline in samples derived from pig farms were higher than those of samples harvested from other aquatic environments. These findings suggest that the high concentrations of antimicrobials observed in these aquatic environments likely select for ARGs. Furthermore, they indicate that Aeromonas spp. comprise an effective marker for monitoring antimicrobial resistance in aquatic environments.

  12. Cooperation, cheating, and collapse in biological populations

    Science.gov (United States)

    Gore, Jeff

    2014-03-01

    Natural populations can collapse suddenly in response to small changes in environmental conditions, and recovery from such a collapse can be difficult. We have used laboratory microbial ecosystems to directly measure theoretically proposed early warning signals of impending population collapse. Yeast cooperatively break down the sugar sucrose, meaning that below a critical size the population cannot sustain itself. We have demonstrated experimentally that changes in the fluctuations of the population size can serve as an early warning signal that the population is close to collapse. The cooperative nature of yeast growth on sucrose suggests that the population may be susceptible to ``cheater'' cells, which do not contribute to the public good and instead merely take advantage of the cooperative cells. We confirm this possibility experimentally and find that such social parasitism decreases the resilience of the population.

  13. State-of-the-Art-Review of Collapsible Soils

    Directory of Open Access Journals (Sweden)

    A. A. AL-Rawas

    2000-12-01

    Full Text Available Collapsible soils are encountered in arid and semi-arid regions. Such soils cause potential construction problems due to their collapse upon wetting. The collapse phenomenon is primarily related to the open structure of the soil. Several soil collapse classifications based on parameters such as moisture content, dry density, Atterberg limits and clay content have been proposed in the literature as indicators of the soil collapse potential. Direct measurement of the magnitude of collapse, using laboratory and/or field tests, is essential once a soil showed indications of collapse potential. Treatment methods such as soil replacement, compaction control and chemical stabilization showed significant reduction in the settlement of collapsible soils. The design of foundations on collapsible soils depends on the depth of the soil, magnitude of collapse and economics of the design. Strip foundations are commonly used when collapsing soil extends to a shallow depth while piles and drilled piers are recommended in cases where the soil extends to several meters. This paper provides a comprehensive review of collapsible soils. These include the different types of collapsible soils, mechanisms of collapse, identification and classification methods, laboratory and field testing, treatment methods and guidelines for foundation design.

  14. Collapse risk of buildings in the Pacific Northwest region due to subduction earthquakes

    Science.gov (United States)

    Raghunandan, Meera; Liel, Abbie B.; Luco, Nicolas

    2015-01-01

    Subduction earthquakes similar to the 2011 Japan and 2010 Chile events will occur in the future in the Cascadia subduction zone in the Pacific Northwest. In this paper, nonlinear dynamic analyses are carried out on 24 buildings designed according to outdated and modern building codes for the cities of Seattle, Washington, and Portland, Oregon. The results indicate that the median collapse capacity of the ductile (post-1970) buildings is approximately 40% less when subjected to ground motions from subduction, as compared to crustal earthquakes. Buildings are more susceptible to earthquake-induced collapse when shaken by subduction records (as compared to crustal records of the same intensity) because the subduction motions tend to be longer in duration due to their larger magnitude and the greater source-to-site distance. As a result, subduction earthquakes are shown to contribute to the majority of the collapse risk of the buildings analyzed.

  15. Compositional variations of zirconolite from the Evate apatite deposit (Mozambique) as an indicator of magmatic-hydrothermal conditions during post-orogenic collapse of Gondwana

    Science.gov (United States)

    Hurai, Vratislav; Huraiová, Monika; Gajdošová, Michaela; Konečný, Patrik; Slobodník, Marek; Siegfried, Pete R.

    2017-11-01

    Zirconolite is documented from the Evate apatite-magnetite-carbonate deposit in the circular Monapo Klippe (eastern Mozambique)—a relic of Neoproterozoic nappe thrusted over the Mesoproterozoic basement of the Nampula block. Zirconolite enriched in rare earth elements—REE = Y + Lu+ΣLa-Yb (up to 24.11 wt% REE2O3, 0.596 apfu REE) creates thin rims around spinel and magnetite grains, whereas zirconolite enriched in U and Th (up to 18.88 wt% ThO2 + UO2, 0.293 apfu Th + U) replace the Late Ediacaran ( 590 Ma) zircon and baddeleyite along contacts with pyrrhotite and magnetite. Both types of zirconolite contain locally increased Nb and Ta concentrations (up to 7.58 wt% Nb2O5 + Ta2O5, 0.202 apfu Nb + Ta). Typical substitutions in zirconolite from Evate involve REE + U,Th → Ca, and M 2++M 5+→Ti + M 3+ (M 2+ = Fe2++Mg, M 3+ = Fe3+, M 5+ = Nb5++Ta5+). In addition, REE-zirconolite is typical of the REE + M 2+ → Ca + M 3+ substitution (M 2+ = Mg, M 3+ = Fe3++Al3+). Hence, Fe3+ predominates over Fe2+ in all types of zirconolite, thus enabling the high REE content in Nb-poor zirconolites to be stored in locally dominant REEZrTiFe3+O7 component known so far only as a synthetic analogue of natural zirconolite. Other types of zirconolite from Evate are dominated by the common CaZrTi2O7 end member, but the aforementioned "synthetic" REEZrTiFe3+O7 accompanied by another `synthetic' (U,Th)ZrFe3 + 2O7 component are also abundant. The U,Pb,Th concentrations in U,Th-zirconolites plot discordantly to theoretical isochrons, thus indicating 440 ppm of non-radiogenic excess lead in earlier Nb-rich zirconolite contrasting with secondary Pb loss from later Nb-poor zirconolite. The non-radiogenic Pb-corrected age of the early zirconolite corresponded to 485 ± 9 Ma, within uncertainty limit identical with the 493 ± 10 Ma age of the associated uranothorianite. The variegated chemical composition of zirconolites reflects the complex history of the Evate deposit. Compositional and

  16. Cosmogenesis and Collapse

    Science.gov (United States)

    Pearle, Philip

    2012-01-01

    Some possible benefits of dynamical collapse for a quantum theory of cosmogenesis are discussed. These are a possible long wait before creation begins, creation of energy and space, and choice of a particular universe out of a superposition.

  17. Cosmogenesis and Collapse

    CERN Document Server

    Pearle, Philip

    2010-01-01

    Some possible benefits of dynamical collapse for a quantum theory of cosmogenesis are discussed. These are a possible long wait before creation begins, creation of energy and space, and choice of a particular universe out of a superposition.

  18. Chronogenesis, Cosmogenesis and Collapse

    OpenAIRE

    Pearle, Philip

    2012-01-01

    A simple quantum model describing the onset of time is presented. This is combined with a simple quantum model of the onset of space. A major purpose is to explore the interpretational issues which arise. The state vector is a superposition of states representing "instants." The sample space and probability measure are discussed. Critical to the dynamics is state vector collapse: it is argued that a tenable interpretation is not possible without it. Collapse provides a mechanism whereby the u...

  19. Cell wall-related genes studies on peach cultivars with differential susceptibility to woolliness: looking for candidates as indicators of chilling tolerance.

    Science.gov (United States)

    Genero, Melisa; Gismondi, Mauro; Monti, Laura L; Gabilondo, Julieta; Budde, Claudio O; Andreo, Carlos S; Lara, María V; Drincovich, María F; Bustamante, Claudia A

    2016-06-01

    The results obtained indicate that a β-xylosidase gene may act as good indicator of chilling tolerance and provide new insights into the complex issue of peach fruit woolliness. The storage of peaches at low temperatures for prolonged periods can induce a form of chilling injury (CI) called woolliness, characterized by a lack of juiciness and a mealy texture. As this disorder has been associated with abnormal cell wall dismantling, the levels of 12 transcripts encoding proteins involved in cell wall metabolism were analysed in cultivars with contrasting susceptibility to this disorder selected from five melting flesh peach cultivars. The resistant ('Springlady') and susceptible ('Flordaking') cultivars displayed differences in the level of expression of some of the selected genes during fruit softening and in woolly versus non-woolly fruits. From these genes, the level of expression of PpXyl, which encodes for a putative β-xylosidase, was the one that presented the highest correlation (negative) with the susceptibility to woolliness. PpXyl expression was also analysed in a cultivar ('Rojo 2') with intermediate susceptibility to woolliness, reinforcing the conclusion about the correlation of PpXyl expression to the presence of woolliness symptom. Moreover, the level of expression of PpXyl correlated to protein level detected by Western blot. Analyses of the promoter region of the PpXyl gene (1637 bp) isolated from the three cultivars showed no differences suggesting that cis-elements from other regions of the genome and/or trans elements could be responsible of the differential PpXyl expression patterns. Overall, the results obtained indicate that PpXyl may act as a good indicator of woolliness tolerance and that the regulation of expression of this gene in different cultivars does not depend on sequences upstream the coding sequence.

  20. Collapsed Dark Matter Structures

    Science.gov (United States)

    Buckley, Matthew R.; DiFranzo, Anthony

    2018-02-01

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  1. Collapsed Dark Matter Structures.

    Science.gov (United States)

    Buckley, Matthew R; DiFranzo, Anthony

    2018-02-02

    The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

  2. Heterogeneous Responses to Antioxidants in Noradrenergic Neurons of the Locus Coeruleus Indicate Differing Susceptibility to Free Radical Content

    Science.gov (United States)

    de Oliveira, Ramatis B.; Gravina, Fernanda S.; Lim, Rebecca; Brichta, Alan M.; Callister, Robert J.; van Helden, Dirk F.

    2012-01-01

    The present study investigated the effects of the antioxidants trolox and dithiothreitol (DTT) on mouse Locus coeruleus (LC) neurons. Electrophysiological measurement of action potential discharge and whole cell current responses in the presence of each antioxidant suggested that there are three neuronal subpopulations within the LC. In current clamp experiments, most neurons (55%; 6/11) did not respond to the antioxidants. The remaining neurons exhibited either hyperpolarization and decreased firing rate (27%; 3/11) or depolarization and increased firing rate (18%; 2/11). Calcium and JC-1 imaging demonstrated that these effects did not change intracellular Ca2+ concentration but may influence mitochondrial function as both antioxidant treatments modulated mitochondrial membrane potential. These suggest that the antioxidant-sensitive subpopulations of LC neurons may be more susceptible to oxidative stress (e.g., due to ATP depletion and/or overactivation of Ca2+-dependent pathways). Indeed it may be that this subpopulation of LC neurons is preferentially destroyed in neurological pathologies such as Parkinson's disease. If this is the case, there may be a protective role for antioxidant therapies. PMID:22577493

  3. Chronogenesis, Cosmogenesis and Collapse

    Science.gov (United States)

    Pearle, Philip

    2013-06-01

    A simple quantum model describing the onset of time is presented. This is combined with a simple quantum model of the onset of space. A major purpose is to explore the interpretational issues which arise. The state vector is a superposition of states representing different "instants." The sample space and probability measure are discussed. Critical to the dynamics is state vector collapse: it is argued that a tenable interpretation is not possible without it. Collapse provides a mechanism whereby the universe size, like a clock, is narrowly correlated with the quantized time eigenvalues.

  4. Antimicrobial susceptibility of streptococci from various indications of swine, horses, dogs and cats as determined in the BfT-GermVet monitoring program 2004-2006.

    Science.gov (United States)

    Schwarz, Stefan; Alesík, Eva; Grobbel, Mirjam; Lübke-Becker, Antina; Werckenthin, Christiane; Wieler, Lothar H; Wallmann, Jürgen

    2007-01-01

    A total of 500 streptococci from two indications of swine (beta-haemolytic streptococci from infections of the urinary/genital tract including strains from the mastitis metritis agalactia syndrome as well as S. suis from infections of the central nervous system and the musculoskeletal system), two indications of horses (S. equi from respiratory tract infections and beta-haemolytic streptococci from infections of the genital tract), as well as three indications of dogs and cats (beta-haemolytic streptococci from infections of the respiratory tract, the urinary/genital tract, and skin/ear/mouth) were investigated for their susceptibility to antimicrobial agents. Regardless of the animal origin and indication, the most frequently detected resistance properties were resistances against sulfamethoxazole (20-78%), tetracycline (17-93%) as well as gentamicin (14-79%). Resistance to penicillins or cephalosporins was very rarely detected - if at all.

  5. Quantum dust collapse in 2+1 dimensions

    CERN Document Server

    Sarkar, Souvik; Wijewardhana, L C R

    2016-01-01

    In this paper we will examine the consequence of a canonical theory of quantum dust collapse in 2+1 dimensions. The solution of the WDW equation describing the collapse indicates that collapsing shells outside the apparent horizon are accompanied by outgoing shells within the apparent horizon during their collapse phase and stop collapsing once they reach the apparent horizon. Taking this picture of quantum collapse seriously, we determine a static solution with energy density corresponding to a dust ball whose collapse has terminated at the apparent horizon. We show that the boundary radius of the ball is larger than the BTZ radius confirming that no event horizon is formed. The ball is sustained by radial pressure which we determine and which we attribute to the Unruh radiation within it.

  6. COLLAPSED BUILDINGS IN NIGERIA

    African Journals Online (AJOL)

    Global Journal

    2016-05-23

    May 23, 2016 ... STRUCTURAL. FAILURES. Ajayi (1988) has attributed building failures and collapse in Nigeria to poor design of structure and foundation detailing. ... contributors to structural failures in buildings. ... A. E. Archibong, Department of Architecture, Cross River University of Technology, Calabar, Nigeria.

  7. Modeling Core Collapse Supernovae

    Science.gov (United States)

    Mezzacappa, Anthony

    2017-01-01

    Core collapse supernovae, or the death throes of massive stars, are general relativistic, neutrino-magneto-hydrodynamic events. The core collapse supernova mechanism is still not in hand, though key components have been illuminated, and the potential for multiple mechanisms for different progenitors exists. Core collapse supernovae are the single most important source of elements in the Universe, and serve other critical roles in galactic chemical and thermal evolution, the birth of neutron stars, pulsars, and stellar mass black holes, the production of a subclass of gamma-ray bursts, and as potential cosmic laboratories for fundamental nuclear and particle physics. Given this, the so called ``supernova problem'' is one of the most important unsolved problems in astrophysics. It has been fifty years since the first numerical simulations of core collapse supernovae were performed. Progress in the past decade, and especially within the past five years, has been exponential, yet much work remains. Spherically symmetric simulations over nearly four decades laid the foundation for this progress. Two-dimensional modeling that assumes axial symmetry is maturing. And three-dimensional modeling, while in its infancy, has begun in earnest. I will present some of the recent work from the ``Oak Ridge'' group, and will discuss this work in the context of the broader work by other researchers in the field. I will then point to future requirements and challenges. Connections with other experimental, observational, and theoretical efforts will be discussed, as well.

  8. Collapsing Enormous Stars

    Science.gov (United States)

    Kohler, Susanna

    2015-09-01

    One of the big puzzles in astrophysics is how supermassive black holes (SMBHs) managed to grow to the large sizes weve observed in the very early universe. In a recent study, a team of researchers examines the possibility that they were formed by the direct collapse of supermassive stars.Formation MysterySMBHs billions of times as massive as the Sun have been observed at a time when the universe was less than a billion years old. But thats not enough time for a stellar-mass black hole to grow to SMBH-size by accreting material so another theory is needed to explain the presence of these monsters so early in the universes history. A new study, led by Tatsuya Matsumoto (Kyoto University, Japan), poses the following question: what if supermassive stars in the early universe collapsed directly into black holes?Previous studies of star formation in the early universe have suggested that, in the hot environment of these primordial times, stars might have been able to build up mass much faster than they can today. This could result in early supermassive stars roughly 100,000 times more massive than the Sun. But if these early stars end their lives by collapsing to become massive black holes in the same way that we believe massive stars can collapse to form stellar-mass black holes today this should result in enormously violent explosions. Matusmoto and collaborators set out to model this process, to determine what we would expect to see when it happens!Energetic BurstsThe authors modeled the supermassive stars prior to collapse and then calculated whether a jet, created as the black hole grows at the center of the collapsing star, would be able to punch out of the stellar envelope. They demonstrated that the process would work much like the widely-accepted collapsar model of massive-star death, in which a jet successfully punches out of a collapsing star, violently releasing energy in the form of a long gamma-ray burst (GRB).Because the length of a long GRB is thought to

  9. Mapping flood and flooding potential indices: a methodological approach to identifying areas susceptible to flood and flooding risk. Case study: the Prahova catchment (Romania)

    Science.gov (United States)

    Zaharia, Liliana; Costache, Romulus; Prăvălie, Remus; Ioana-Toroimac, Gabriela

    2017-04-01

    Given that floods continue to cause yearly significant worldwide human and material damages, flood risk mitigation is a key issue and a permanent challenge in developing policies and strategies at various spatial scales. Therefore, a basic phase is elaborating hazard and flood risk maps, documents which are an essential support for flood risk management. The aim of this paper is to develop an approach that allows for the identification of flash-flood and flood-prone susceptible areas based on computing and mapping of two indices: FFPI (Flash-Flood Potential Index) and FPI (Flooding Potential Index). These indices are obtained by integrating in a GIS environment several geographical variables which control runoff (in the case of the FFPI) and favour flooding (in the case of the FPI). The methodology was applied in the upper (mountainous) and middle (hilly) catchment of the Prahova River, a densely populated and socioeconomically well-developed area which has been affected repeatedly by water-related hazards over the past decades. The resulting maps showing the spatialization of the FFPI and FPI allow for the identification of areas with high susceptibility to flashfloods and flooding. This approach can provide useful mapped information, especially for areas (generally large) where there are no flood/hazard risk maps. Moreover, the FFPI and FPI maps can constitute a preliminary step for flood risk and vulnerability assessment.

  10. Collapse settlement in compacted soils

    CSIR Research Space (South Africa)

    Booth, AR

    1977-01-01

    Full Text Available Research into collapse settlement in compacted soils is described, with special reference to recent cases in Southern Africa where collapse settlement occurred in road embankments following wetting of the soil. The laboratory work described...

  11. Collapse of an antibubble.

    Science.gov (United States)

    Zou, Jun; Ji, Chen; Yuan, BaoGang; Ruan, XiaoDong; Fu, Xin

    2013-06-01

    In contrast to a soap bubble, an antibubble is a liquid globule surrounded by a thin film of air. The collapse behavior of an antibubble is studied using a high-speed video camera. It is found that the retraction velocity of the thin air film of antibubbles depends on the thickness of the air film, e, the surface tension coefficient σ, etc., and varies linearly with (σ/ρe)(1/2), according to theoretical analysis and experimental observations. During the collapse of the antibubble, many tiny bubbles can be formed at the rim of the air film due to the Rayleigh instability. In most cases, a larger bubble will emerge finally, which holds most of the volume of the air film.

  12. Shock induced cavity collapse

    Science.gov (United States)

    Skidmore, Jonathan; Doyle, Hugo; Tully, Brett; Betney, Matthew; Foster, Peta; Ringrose, Tim; Ramasamy, Rohan; Parkin, James; Edwards, Tom; Hawker, Nicholas

    2016-10-01

    Results from the experimental investigation of cavity collapse driven by a strong planar shock (>6km/s) are presented. Data from high speed framing cameras, laser backlit diagnostics and time-resolved pyromety are used to validate the results of hydrodynamic front-tracking simulations. As a code validation exercise, a 2-stage light gas gun was used to accelerate a 1g Polycarbonate projectile to velocities exceeding 6km/s; impact with a PMMA target containing a gas filled void results in the formation of a strong shockwave with pressures exceeding 1Mbar. The subsequent phenomena associated with the collapse of the void and excitation of the inert gas fill are recorded and compared to simulated data. Variation of the mass density and atomic number of the gas fill is used to alter the plasma parameters furthering the extent of the code validation.

  13. Axisymmetric collapses of granular columns

    Science.gov (United States)

    Lube, Gert; Huppert, Herbert E.; Sparks, R. Stephen J.; Hallworth, Mark A.

    2004-06-01

    Experimental observations of the collapse of initially vertical columns of small grains are presented. The experiments were performed mainly with dry grains of salt or sand, with some additional experiments using couscous, sugar or rice. Some of the experimental flows were analysed using high-speed video. There are three different flow regimes, dependent on the value of the aspect ratio a {=} h_i/r_i, where h_i and r_i are the initial height and radius of the granular column respectively. The differing forms of flow behaviour are described for each regime. In all cases a central, conically sided region of angle approximately 59(°) , corresponding to an aspect ratio of 1.7, remains undisturbed throughout the motion. The main experimental results for the final extent of the deposit and the time for emplacement are systematically collapsed in a quantitative way independent of any friction coefficients. Along with the kinematic data for the rate of spread of the front of the collapsing column, this is interpreted as indicating that frictional effects between individual grains in the bulk of the moving flow only play a role in the last instant of the flow, as it comes to an abrupt halt. For a {reach r_infty is given by t_infty {=} 3(h_i/g)(1/2} {=} 3(r_i/g)({1/2}a^{1/2)) , where g is the gravitational acceleration. The insights and conclusions gained from these experiments can be applied to a wide range of industrial and natural flows of concentrated particles. For example, the observation of the rapid deposition of the grains can help explain details of the emplacement of pyroclastic flows resulting from the explosive eruption of volcanoes.

  14. Gravitational Waves from Gravitational Collapse.

    Science.gov (United States)

    Fryer, Chris L; New, Kimberly C B

    2011-01-01

    Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars. Supplementary material is available for this article at 10.12942/lrr-2011-1.

  15. Gravitational waves from gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; New, Kimberly C [Los Alamos National Laboratory

    2008-01-01

    Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  16. Gravitational Waves from Gravitational Collapse

    Directory of Open Access Journals (Sweden)

    Chris L. Fryer

    2011-01-01

    Full Text Available Gravitational-wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion-induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.

  17. Laryngeal collapse in seven brachycephalic puppies.

    Science.gov (United States)

    Pink, J J; Doyle, R S; Hughes, J M L; Tobin, E; Bellenger, C R

    2006-03-01

    To document the histories, clinical findings, and management of seven puppies with laryngeal collapse occurring secondarily to brachycephalic airway syndrome. Seven brachycephalic puppies aged between 4.5 and six months underwent surgery for management of brachycephalic airway syndrome following presentation for exercise intolerance and increased respiratory noise and effort. Stenotic nares of varying severity and an elongated soft palate were common to all dogs. All dogs had tracheal hypoplasia and this was severe in four dogs. Laryngeal collapse was present in all dogs. Two dogs had stage I, four dogs stage II, and one dog stage III laryngeal collapse. The dog with stage III laryngeal collapse and one dog with stage II laryngeal collapse died. There was no apparent association between the changes evident on thoracic radiographs or the degree of tracheal hypoplasia and postoperative outcome. The development of severe secondary laryngeal changes in dogs aged six months or less supports the suggestion that immature brachycephalic dogs should undergo assessment and, if indicated, surgery as soon as any clinical signs of BAS are apparent.

  18. PREFACE: Collapse Calderas Workshop

    Science.gov (United States)

    Gottsmann, Jo; Aguirre-Diaz, Gerardo

    2008-10-01

    Caldera-formation is one of the most awe-inspiring and powerful displays of nature's force. Resultant deposits may cover vast areas and significantly alter the immediate topography. Post-collapse activity may include resurgence, unrest, intra-caldera volcanism and potentially the start of a new magmatic cycle, perhaps eventually leading to renewed collapse. Since volcanoes and their eruptions are the surface manifestation of magmatic processes, calderas provide key insights into the generation and evolution of large-volume silicic magma bodies in the Earth's crust. Despite their potentially ferocious nature, calderas play a crucial role in modern society's life. Collapse calderas host essential economic deposits and supply power for many via the exploitation of geothermal reservoirs, and thus receive considerable scientific, economic and industrial attention. Calderas also attract millions of visitors world-wide with their spectacular scenic displays. To build on the outcomes of the 2005 calderas workshop in Tenerife (Spain) and to assess the most recent advances on caldera research, a follow-up meeting was proposed to be held in Mexico in 2008. This abstract volume presents contributions to the 2nd Calderas Workshop held at Hotel Misión La Muralla, Querétaro, Mexico, 19-25 October 2008. The title of the workshop `Reconstructing the evolution of collapse calderas: Magma storage, mobilisation and eruption' set the theme for five days of presentations and discussions, both at the venue as well as during visits to the surrounding calderas of Amealco, Amazcala and Huichapan. The multi-disciplinary workshop was attended by more than 40 scientist from North, Central and South America, Europe, Australia and Asia. Contributions covered five thematic topics: geology, geochemistry/petrology, structural analysis/modelling, geophysics, and hazards. The workshop was generously supported by the International Association of Volcanology and the Chemistry of The Earth's Interior

  19. Cooperation, cheating, and collapse in microbial populations

    Science.gov (United States)

    Gore, Jeff

    2012-02-01

    Natural populations can suffer catastrophic collapse in response to small changes in environmental conditions, and recovery after such a collapse can be exceedingly difficult. We have used laboratory yeast populations to study proposed early warning signals of impending extinction. Yeast cooperatively breakdown the sugar sucrose, meaning that there is a minimum number of cells required to sustain the population. We have demonstrated experimentally that the fluctuations in the population size increase in magnitude and become slower as the population approaches collapse. The cooperative nature of yeast growth on sucrose suggests that the population may be susceptible to cheater cells, which do not contribute to the public good and instead merely take advantage of the cooperative cells. We have confirmed this possibility experimentally by using a cheater yeast strain that lacks the gene encoding the cooperative behavior [1]. However, recent results in the lab demonstrate that the presence of a bacterial competitor may drive cooperation within the yeast population.[4pt] [1] Gore et al, Nature 459, 253 -- 256 (2009)

  20. The Nimitz Freeway Collapse

    Science.gov (United States)

    Feldman, Bernard J.

    2004-10-01

    One of the most tragic sights created by the Loma Prieta earthquake of Oct. 17, 1989, was the collapse of the double-deck Nimitz Freeway (the Cypress Street Viaduct on Interstate 880) just south and east of the San Francisco-Oakland Bay Bridge in Oakland. Along a 1.4-km north-south stretch, the upper deck of the freeway fell on top of the lower deck of the freeway, killing 42 motorists (see Fig. 1). Even though the earthquake occurred during rush hour (5:04 p.m.), traffic was extremely light that day because the third game of the World Series between the Oakland Athletics and the San Francisco Giants was about to begin and many commuters were already at home in front of their television sets.

  1. Structural control on karst collapse sinkhole formation

    Science.gov (United States)

    Santo, Antonio; Ascione, Alessandra; Mazzoli, Stefano; Santangelo, Nicoletta

    2013-04-01

    Collapse sinkholes owing their formation to erosion and deformation phenomena caused by subsurface karstification are widespread in the carbonate massifs of peninsular Italy. In contrast with solution dolines, which are densely distributed on the subplanar top surfaces of the carbonate massifs, the collapse sinkholes (hereinafter labelled karst collapse sinkholes) generally occur as isolated landforms and mostly affect the slopes and piedmont areas. In the latter instances, the sinkholes also affect alluvial fan conglomerates, or slope debris, overlying the carbonate rocks. We investigated the karst collapse sinkholes of the southern-central Apennines mountain belt (Italy), which is representative of a young orogenic system, characterised by recent tectonic activity and strong seismicity. The aim of the study is the identification of the causative factors which control the occurrence of such hazardous phenomena. The study was based on a regional scale analysis on sinkhole distribution in relation to the local geological-structural, geomorphological and hydrogeological contexts, and was paralleled with field analysis of some selected areas. The regional scale analysis indicates that the karst collapse sinkholes are not the mere response to the concurrence of the climatic and lithological conditions which commonly favour the development of karst processes, the occurrence of such landforms appearing strongly influenced by distinctive structural and hydrogeological conditions. In particular, a close relationship between the karst collapse sinkholes and the main extensional faults showing evidence of late Quaternary activity may be envisaged. This is inferred from the spatial distribution of the karst collapse sinkholes, which is strikingly uneven, the sinkholes generally occurring in alignments following large late Quaternary fault zones, or being clustered at the terminations of those faults. In addition, areas affected by the occurrence of groups of sinkholes, are

  2. Spherical Collapse in Chameleon Models

    CERN Document Server

    Brax, Ph; Steer, D A

    2010-01-01

    We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse depends on the initial comoving size of the inhomogeneity.

  3. Astrophysics of Collapsing Axion Stars

    Science.gov (United States)

    Eby, Joshua; Leembruggen, Madelyn; Suranyi, Peter; Wijewardhana, L. C. R.

    2017-01-01

    Axion stars are condensed states of large numbers of axion particles, bound by self-gravitation and quantum self-interactions. The mass of weakly bound axion stars is limited by gravitational stability, with condensates exceeding the maximum mass subject to collapse. During the collapse process, the axion density increases and higher-order self-interactions become increasingly relevant. By taking these terms into account, we provide evidence that in spite of a leading attractive interaction, collapsing axion stars stabilize in a dense state which is larger than its Schwarzschild radius, and so do not form black holes. During the last moments of collapse, number changing processes take place in the axion star with a very large rate, leading to emission of many highly energetic axions which escape from galaxies and galaxy clusters. Finally, if axion stars are a significant fraction of cold dark matter, then frequent collisions with each other or with ordinary stars could catalyze this collapse process as well.

  4. Simultaneous monitoring of a collapsing landslide with video cameras

    Directory of Open Access Journals (Sweden)

    K. Fujisawa

    2008-01-01

    Full Text Available Effective countermeasures and risk management to reduce landslide hazards require a full understanding of the processes of collapsing landslides. While the processes are generally estimated from the features of debris deposits after collapse, simultaneous monitoring during collapse provides more insights into the processes. Such monitoring, however, is usually very difficult, because it is rarely possible to predict when a collapse will occur. This study introduces a rare case in which a collapsing landslide (150 m in width and 135 m in height was filmed with three video cameras in Higashi-Yokoyama, Gifu Prefecture, Japan. The cameras were set up in the front and on the right and left sides of the slide in May 2006, one month after a series of small slope failures in the toe and the formation of cracks on the head indicated that a collapse was imminent.

    The filmed images showed that the landslide collapse started from rock falls and slope failures occurring mainly around the margin, that is, the head, sides and toe. These rock falls and slope failures, which were individually counted on the screen, increased with time. Analyzing the images, five of the failures were estimated to have each produced more than 1000 m3 of debris, and the landslide collapsed with several surface failures accompanied by a toppling movement. The manner of the collapse suggested that the slip surface initially remained on the upper slope, and then extended down the slope as the excessive internal stress shifted downwards. Image analysis, together with field measurements using a ground-based laser scanner after the collapse, indicated that the landslide produced a total of 50 000 m3 of debris.

    As described above, simultaneous monitoring provides valuable information about landslide processes. Further development of monitoring techniques will help clarify landslide processes qualitatively as well as quantitatively.

  5. Three Ulcerative Colitis Susceptibility Loci Are Associated with Primary Sclerosing Cholangitis and Indicate a Role for IL2, REL, and CARD9

    NARCIS (Netherlands)

    Janse, Marcel; Lamberts, Laetitia E.; Franke, Lude; Raychaudhuri, Soumya; Ellinghaus, Eva; Boberg, Kirsten Muri; Melum, Espen; Folseraas, Trine; Schrumpf, Erik; Bergquist, Annika; Bjornsson, Einar; Fu, Jingyuan; Westra, Harm Jan; Groen, Harry J. M.; Fehrmann, Rudolf S. N.; Smolonska, Joanna; van den Berg, Leonard H.; Ophoff, Roel A.; Porte, Robert J.; Weismueller, Tobias J.; Wedemeyer, Jochen; Schramm, Christoph; Sterneck, Martina; Guenther, Rainer; Braun, Felix; Vermeire, Severine; Henckaerts, Liesbet; Wijmenga, Cisca; Ponsioen, Cyriel Y.; Schreiber, Stefan; Karlsen, Tom H.; Franke, Andre; Weersma, Rinse K.

    Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by inflammation and fibrosis of the bile ducts. Both environmental and genetic factors contribute to its pathogenesis. To further clarify its genetic background, we investigated susceptibility loci recently

  6. Vibrational Collapse of Hexapod Packings

    Science.gov (United States)

    Zhao, Yuchen; Ding, Jingqiu; Barés, Jonathan; Zheng, Hu; Dierichs, Karola; Menges, Achim; Behringer, Robert

    2017-06-01

    Columns made of convex noncohesive grains like sand collapse after being released from a confining container. However, structures built from non-convex grains can be stable without external support. In the current experiments, we investigate the effect of vibration on destroying such columns. The change of column height during vertical vibration, can be well characterized by stretched exponential relaxation when the column is short, which is in agreement with previous work, while a faster collapse happens when the column is tall. We investigate the collapse after the fast process including its dependence on column geometry, and on interparticle and basal friction.

  7. Predicting mining collapse: Superjerks and the appearance of record-breaking events in coal as collapse precursors

    Science.gov (United States)

    Jiang, Xiang; Liu, Hanlong; Main, Ian G.; Salje, Ekhard K. H.

    2017-08-01

    The quest for predictive indicators for the collapse of coal mines has led to a robust criterion from scale-model tests in the laboratory. Mechanical collapse under uniaxial stress forms avalanches with a power-law probability distribution function of radiated energy P ˜E-ɛ , with exponent ɛ =1.5 . Impending major collapse is preceded by a reduction of the energy exponent to the mean-field value ɛ =1.32 . Concurrently, the crackling noise increases in intensity and the waiting time between avalanches is reduced when the major collapse is approaching. These latter criteria were so-far deemed too unreliable for safety assessments in coal mines. We report a reassessment of previously collected extensive collapse data sets using "record-breaking analysis," based on the statistical appearance of "superjerks" within a smaller spectrum of collapse events. Superjerks are defined as avalanche signals with energies that surpass those of all previous events. The final major collapse is one such superjerk but other "near collapse" events equally qualify. In this way a very large data set of events is reduced to a sparse sequence of superjerks (21 in our coal sample). The main collapse can be anticipated from the sequence of energies and waiting times of superjerks, ignoring all weaker events. Superjerks are excellent indicators for the temporal evolution, and reveal clear nonstationarity of the crackling noise at constant loading rate, as well as self-similarity in the energy distribution of superjerks as a function of the number of events so far in the sequence Es j˜nδ with δ =1.79 . They are less robust in identifying the precise time of the final collapse, however, than the shift of the energy exponents in the whole data set which occurs only over a short time interval just before the major event. Nevertheless, they provide additional diagnostics that may increase the reliability of such forecasts.

  8. New Insights into the Geography and Modelling of Wind Erosion in the European Agricultural Land. Application of a Spatially Explicit Indicator of Land Susceptibility to Wind Erosion

    Directory of Open Access Journals (Sweden)

    Pasquale Borrelli

    2015-07-01

    Full Text Available The current state of the art in erosion research does not provide answers about the “where” and “when” of wind erosion in European agricultural lands. Questions about the implications for the agricultural productivity remain unanswered. Tackling this research gap, the study provides a more comprehensive understanding of the spatial patterns of land susceptibility to wind erosion in European agricultural lands. The Index of Land Susceptibility to Wind Erosion (ILSWE was applied in a GIS environment. A harmonized input dataset ranked following a fuzzy logic technique was employed. Within the 36 European countries under investigation, moderate (17.3 million ha and high levels (8.8 million ha of land susceptibility to wind erosion were predicted. This corresponds to 8.0% and 4.1% of total agricultural land, respectively.

  9. Collapse of the Late Proterozoic ecosystem

    Science.gov (United States)

    Schopf, J. W.

    1991-01-01

    Evidence accumulated over the past two decades is now sufficient to permit an initial quantitative assessment of the patterns of biotic diversity and extinction that occurred during Proterozoic time. Because of limitations in both the quality and quantity of data currently available, however, generalizations thus derived must be regarded as tentative. Nevertheless, read literally, available palaeontological data appear to indicate that the global ecosystem experienced a gradual but massive collapse between 1 000 Ma and the beginning of the Phanerozoic, a supposition consistent with other lines of geological and geochemical evidence. A possible forcing agent for such a collapse appears to have been a decrease in ambient levels of carbon dioxide and a resultant decrease in average global temperature, photosynthetic efficiency, and primary productivity.

  10. Seismic Progressive Collapse: Qualitative Point of View

    Directory of Open Access Journals (Sweden)

    H. Wibowo

    2009-01-01

    Full Text Available Progressive collapse is a catastrophic structural phenomenon that can occur because of human-made and natural hazards. In progressive collapse mechanism, a single local failure may cause a significant deformation which then may lead to collapse of a structure. The current practices in progressive collapse analysis and design method generally focus on preventing progressive collapse due to abnormal gravity and blast loads. Progressive collapse behaviour of structures due to earthquake loads has not received as much attention. This paper presents a brief overview of the current state-of-knowledge, insights, and issues related to progressive collapse behaviour of structures caused by earthquake loading.

  11. Ground deformations in collapsed caldera structures

    Science.gov (United States)

    De Natale, Giuseppe; Pingue, Folco

    1993-09-01

    A method is presented to analyze the effect of stress-strain discontinuities on the ground deformations generated by a pressure source. This is meant to simulate the effects due to caldera structures, likely to present fractured zones at the borders of the collapsed area. A method originally developed by Crouch (1976) to solve plane-strain problems has been used to simulate deformation curves for several source and discontinuity geometries. The main result is that the location of the discontinuities controls the extension of the deformed zone, and always reduces it with respect to a continuous medium. With respect to a homogeneous medium the presence of lateral discontinuities also acts towards lowering the overpressure required to produce a given amount of deformation. These results indicate that, when analyzing ground deformations in calderas, the use of classical methods involving continuous media should be avoided, or at least taken with caution. These methods, in fact, assume that the extension of the deformed zone is only linked to the source depth. Some examples of ground deformations in active calderas have been analyzed in the framework of the results obtained from theoretical modeling. Four calderas recently affected by ground deformations have been considered: Rabaul (New Guinea), Campi Flegrei (Italy), Long Valley and Yellowstone (U.S.A.). The effects of collapsed structures on the deformation field are possibly evidenced for all the four calderas. At Rabaul and Campi Flegrei, the fracture systems mainly affecting the ground deformations probably represent younger, innermost collapses and are well evidenced by seismicity studies. Ground deformations are here concentrated in an area much smaller than the one enclosed by geologically visible caldera rims. In particular, at Rabaul, the effect of the innermost collapse can explain the high concentration of the uplift in the period 1971-1985, previously modeled by a very shallow source (1-3 km) in terms of

  12. Moduli destabilization via gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dong-il [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Pedro, Francisco G. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Yeom, Dong-han [Sogang Univ., Seoul (Korea, Republic of). Center for Quantum Spacetime; Kyoto Univ. (Japan). Yukawa Inst. for Theoretical Physics

    2013-06-15

    We examine the interplay between gravitational collapse and moduli stability in the context of black hole formation. We perform numerical simulations of the collapse using the double null formalism and show that the very dense regions one expects to find in the process of black hole formation are able to destabilize the volume modulus. We establish that the effects of the destabilization will be visible to an observer at infinity, opening up a window to a region in spacetime where standard model's couplings and masses can differ significantly from their background values.

  13. Protostellar Collapse Induced by Compression

    OpenAIRE

    Hennebelle, P.; Whitworth, A. P.; Gladwin, P. P.; Andre, Ph.

    2002-01-01

    We present numerical simulations of the evolution of low-mass, isothermal, molecular cores which are subjected to an increase in external pressure $P\\xt$. If $P\\xt$ increases very slowly, the core approaches instability quite quasistatically. However, for larger (but still quite modest) $dP\\xt/dt$ a compression wave is driven into the core, thereby triggering collapse from the outside in. If collapse of a core is induced by increasing $P\\xt$, this has a number of interesting consequences. (i)...

  14. The widespread collapse of an invasive species: Argentine ants (Linepithema humile) in New Zealand.

    Science.gov (United States)

    Cooling, Meghan; Hartley, Stephen; Sim, Dalice A; Lester, Philip J

    2012-06-23

    Synergies between invasive species and climate change are widely considered to be a major biodiversity threat. However, invasive species are also hypothesized to be susceptible to population collapse, as we demonstrate for a globally important invasive species in New Zealand. We observed Argentine ant populations to have collapsed in 40 per cent of surveyed sites. Populations had a mean survival time of 14.1 years (95% CI = 12.9-15.3 years). Resident ant communities had recovered or partly recovered after their collapse. Our models suggest that climate change will delay colony collapse, as increasing temperature and decreasing rainfall significantly increased their longevity, but only by a few years. Economic and environmental costs of invasive species may be small if populations collapse on their own accord.

  15. The widespread collapse of an invasive species: Argentine ants (Linepithema humile) in New Zealand

    Science.gov (United States)

    Cooling, Meghan; Hartley, Stephen; Sim, Dalice A.; Lester, Philip J.

    2012-01-01

    Synergies between invasive species and climate change are widely considered to be a major biodiversity threat. However, invasive species are also hypothesized to be susceptible to population collapse, as we demonstrate for a globally important invasive species in New Zealand. We observed Argentine ant populations to have collapsed in 40 per cent of surveyed sites. Populations had a mean survival time of 14.1 years (95% CI = 12.9–15.3 years). Resident ant communities had recovered or partly recovered after their collapse. Our models suggest that climate change will delay colony collapse, as increasing temperature and decreasing rainfall significantly increased their longevity, but only by a few years. Economic and environmental costs of invasive species may be small if populations collapse on their own accord. PMID:22130172

  16. Exploring the links between volcano flank collapse and magma evolution: Fogo oceanic shield volcano, Cape Verde

    Science.gov (United States)

    Cornu, Melodie-Neige; Paris, Raphael; Doucelance, Regis; Bachelery, Patrick; Guillou, Hervé

    2017-04-01

    Mass wasting of oceanic shield volcanoes is largely documented through the recognition of collapse scars and submarine debris fans. However, it is actually difficult to infer the mechanisms controlling volcano flank failures that potentially imply tens to hundreds of km3. Studies coupling detailed petrological and geochemical analyses of eruptive products hold clues for better understanding the relationships between magma sources, the plumbing system, and flank instability. Our study aims at tracking potential variations of magma source, storage and transport beneath Fogo shield volcano (Cape Verde) before and after its major flank collapse. We also provide a geochronological framework of this magmatic evolution through new radiometric ages (K-Ar and Ar-Ar) of both pre-collapse and post-collapse lavas. The central part of Fogo volcanic edifice is truncated by an 8 km-wide caldera opened to the East, corresponding to the scar of the last flank collapse (Monte Amarelo collapse, Late Pleistocene, 150 km3). Lavas sampled at the base of the scar (the so-called Bordeira) yielded ages between 158 and 136 ka. The age of the collapse is constrained between 68 ka (youngest lava flow cut by the collapse scar) and 59 ka (oldest lava flow overlapping the scar). The collapse walls display a complex structural, intrusive and eruptive history. Undersaturated volcanism (SiO2elements analyses indicate that the pre-collapse lavas are significantly less differentiated than post-collapse lavas, with a peak of alkalis at the collapse. Rare-earth elements concentration decreases with time, with a notable positive anomaly before the collapse. The evolution of the isotopic ratios (Sr, Nd and Pb) through time displays unusual V-shaped profiles centered around the collapse. The occurrence of the Monte Amarelo collapse is thus not disconnected from the magmatic evolution, both at the crustal and mantellic levels. Our results also point out the importance and relative frequency of explosive

  17. Antimicrobial susceptibility of coagulase-positive and coagulase-variable Staphylococci from various indications of swine, dogs and cats as determined in the BfT-GermVet monitoring program 2004-2006.

    Science.gov (United States)

    Schwarz, Stefan; Alesík, Eva; Werckenthin, Christiane; Grobbel, Mirjam; Lübke-Becker, Antina; Wieler, Lothar H; Wallmann, Jürgen

    2007-01-01

    A total of 248 coagulase-positive and coagulase-variable staphylococci from two indications of swine (infections of the urinary/genital tract including strains from the mastitis metritis agalactia syndrome as well as infections of the skin) as well as two indications of dogs/cats (respiratory tract infections and infections of skin/ear/mouth) were investigated for their susceptibility to numerous antimicrobial agents. Regardless of the animal origin and indication, the most frequently detected resistance properties were resistances against penicillin G (53-77%) and ampicillin (42-75%), tetracycline (33-52%) as well as erythromycin (13-27%). Oxacillin-resistant staphylococci were rarely detected.

  18. Reduced maximal inhibition in phenotypic susceptibility assays indicates that viral strains resistant to the CCR5 antagonist maraviroc utilize inhibitor-bound receptor for entry.

    Science.gov (United States)

    Westby, Mike; Smith-Burchnell, Caroline; Mori, Julie; Lewis, Marilyn; Mosley, Michael; Stockdale, Mark; Dorr, Patrick; Ciaramella, Giuseppe; Perros, Manos

    2007-03-01

    Maraviroc is a CCR5 antagonist in clinical development as one of a new class of antiretrovirals targeting human immunodeficiency virus type 1 (HIV-1) coreceptor binding. We investigated the mechanism of HIV resistance to maraviroc by using in vitro sequential passage and site-directed mutagenesis. Serial passage through increasing maraviroc concentrations failed to select maraviroc-resistant variants from some laboratory-adapted and clinical isolates of HIV-1. However, high-level resistance to maraviroc was selected from three of six primary isolates passaged in peripheral blood lymphocytes (PBL). The SF162 strain acquired resistance to maraviroc in both treated and control cultures; all resistant variants were able to use CXCR4 as a coreceptor. In contrast, maraviroc-resistant virus derived from isolates CC1/85 and RU570 remained CCR5 tropic, as evidenced by susceptibility to the CCR5 antagonist SCH-C, resistance to the CXCR4 antagonist AMD3100, and an inability to replicate in CCR5 Delta32/Delta32 PBL. Strain-specific mutations were identified in the V3 loop of maraviroc-resistant CC1/85 and RU570. The envelope-encoding region of maraviroc-resistant CC1/85 was inserted into an NL4-3 background. This recombinant virus was completely resistant to maraviroc but retained susceptibility to aplaviroc. Reverse mutation of gp120 residues 316 and 323 in the V3 loop (numbering from HXB2) to their original sequence restored wild-type susceptibility to maraviroc, while reversion of either mutation resulted in a partially sensitive virus with reduced maximal inhibition (plateau). The plateaus are consistent with the virus having acquired the ability to utilize maraviroc-bound receptor for entry. This hypothesis was further corroborated by the observation that a high concentration of maraviroc blocks the activity of aplaviroc against maraviroc-resistant virus.

  19. Collapse of simple harmonic universe

    Energy Technology Data Exchange (ETDEWEB)

    Mithani, Audrey T.; Vilenkin, Alexander, E-mail: audrey.todhunter@tufts.edu, E-mail: vilenkin@cosmos.phy.tufts.edu [Institute of Cosmology, Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States)

    2012-01-01

    In a recent paper Graham et al constructed oscillating and static universe models which are stable with respect to all classical perturbations. Here we show that such universes are quantum-mechanically unstable and can collapse by quantum tunneling to zero radius. We also present instantons describing nucleation of oscillating and static universes from nothing.

  20. Critical behavior of collapsing surfaces

    DEFF Research Database (Denmark)

    Olsen, Kasper; Sourdis, C.

    2009-01-01

    We consider the mean curvature evolution of rotationally symmetric surfaces. Using numerical methods, we detect critical behavior at the threshold of singularity formation resembling that of gravitational collapse. In particular, the mean curvature simulation of a one-parameter family of initial...

  1. Gravitational collapse and naked singularities

    Indian Academy of Sciences (India)

    Gravitational collapse is one of the most striking phenomena in gravitational physics. The cosmic censorship conjecture has provided strong motivation for research in this field. In the absence of a general proof for censorship, many examples have been proposed, in which naked singularity is the outcome of gravitational ...

  2. The collapsed football pla yer

    African Journals Online (AJOL)

    Sello Motaung, BSc, MB ChB, DOH. FIFA Medical Officer and Honorary Part-time Lecturer, Wits Centre for Exercise Science and Sports Medicine, Johannesburg ... parts of the body that may be affected by blows that result in the collapse of a ... temperatures and humidity), especially if players are not acclimatised to such.

  3. Gravitational collapse and naked singularities

    Indian Academy of Sciences (India)

    physical relevance of gravitational collapse is now robust. We have observational evidence for massive and/or supermassive black holes. It is well-understood that there exists an upper limit to the maximum possible mass of a spherical body of cold nuclear matter. We can also naturally consider that black holes may have.

  4. Temperature evolution during dissipative collapse

    Indian Academy of Sciences (India)

    numerous models that noncausal transport equations predict thermodynamical behaviours that can be far .... A radiating model. Following Govender et al [10] we consider a model in which the star undergoes dissipative collapse and evolves to a stable equilibrium state. .... Govender et al [8,9] have shown that the choice.

  5. Spherically symmetric scalar field collapse

    Indian Academy of Sciences (India)

    2013-03-01

    Mar 1, 2013 ... Vaidya metric at the hypersurface and the appropriate junction conditions are obtained. Keywords. Gravitational ... a perfect fluid. As the final stages of collapse might involve dissipative processes as well, ... by Christodoulou [5], Goswami and Joshi [6], Giambo [7] and also by numerical work of. Choptuik [3] ...

  6. Temperature evolution during dissipative collapse

    Indian Academy of Sciences (India)

    Abstract. We investigate the gravitational collapse of a radiating sphere evolving into a final static configuration described by the interior Schwarzschild solution. The temperature profiles of this particular model are obtained within the framework of causal thermodynamics. The overall temperature evolution is enhanced by ...

  7. The Use of a 2,2'-Azobis (2-Amidinopropane) Dihydrochloride Stress Model as an Indicator of Oxidation Susceptibility for Monoclonal Antibodies.

    Science.gov (United States)

    Dion, Michelle Z; Wang, Y John; Bregante, Daniel; Chan, Wayman; Andersen, Nisana; Hilderbrand, Amy; Leiske, Danielle; Salisbury, Cleo M

    2018-02-01

    Protein oxidation is a major pathway for degradation of biologic drug products. Past literature reports have suggested that 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), a free radical generator that produces alkoxyl and alkyl peroxyl radicals, is a useful model reagent stress for assessing the oxidative susceptibility of proteins. Here, we expand the applications of the AAPH model by pairing it with a rapid peptide map method to enable site-specific studies of oxidative susceptibility of monoclonal antibodies and their derivatives for comparison between formats, the evaluation of formulation components, and comparisons across the stress models. Comparing the free radical-induced oxidation model by AAPH with a light-induced oxidation model suggests that light-sensitive residues represent a subset of AAPH-sensitive residues and therefore AAPH can be used as a preliminary screen to highlight molecules that need further assessment by light models. In sum, these studies demonstrate that AAPH stress can be used in multiple ways to evaluate labile residues and oxidation sensitivity as it pertains to developability and manufacturability. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  8. Seeing Core-Collapse Supernovae in the Ultraviolet

    Science.gov (United States)

    Brown, Peter

    Core-collapse supernovae are the catastrophic deaths of massive stars. Ultraviolet observations are needed to understand the energy of the explosion through the study of the bolometric light curves. Early-time ultraviolet observations constrain the size of the progenitor. Ultraviolet spectra can break the degeneracies between temperature/ionization, reddening, and metallicity which hinder our understanding of ultraviolet photometry. Optical observations of high-redshift supernovae probe rest-frame ultraviolet wavelengths, requiring space-based observations of nearby supernovae against which to compare. Ultraviolet observations of core-collapse supernovae can also help distinguish them from type Ia supernovae, enabling cleaner photometric type Ia supernova samples for cosmological measurements. The Ultraviolet/Optical Telescope (UVOT) on the Swift satellite has observed over two hundred core-collapse supernovae in the ultraviolet, including sixty-nine ultraviolet grism spectra of twenty core-collapse SNe. Additional ultraviolet spectra have been obtained by the International Ultraviolet Explorer, Hubble Space Telescope, and Galaxy Evolution Explorer. We propose a project to reduce the Swift grism spectra and combine with the other ultraviolet and groundbased optical/NIR spectra to create time-series bolometric spectra. We will use these bolometric spectra to better understand temperature, reddening, and metallicity and create bolometric light curves of these core collapse SNe. We will also use early time ultraviolet photometry and spectroscopy to constrain the progenitors of core collapse SNe. The ultraviolet observations fill a critical niche in our understanding of core collapse supernovae, and this program will enhance the scientific use of this important dataset from multiple space missions. Beyond core-collapse supernovae, the templates will allow studies of the dust properties around the progenitor systems (including the wavelength dependence of the extinction

  9. Online fuzzy voltage collapse risk quantification

    Energy Technology Data Exchange (ETDEWEB)

    Berizzi, A.; Bovo, C.; Delfanti, M.; Merlo, M. [Politecnico di Milano, 20133 Milano (Italy); Cirio, D. [CESI Ricerca (Italy); Pozzi, M. [CESI (Italy)

    2009-05-15

    Many voltage stability indicators have been proposed in the past for the voltage collapse assessment. Almost all of them are determined through quite complex analytical tools; therefore, it is difficult for system operators to give them a physical meaning. In order to perform a simple and reliable evaluation of the security margins, it is necessary to make a synthesis of the information given by the various indices. The present work proposes an Artificial Intelligence-based tool for the evaluation of the voltage security. In particular, a Fuzzy Inference Engine is developed and optimized by two different approaches (Neural Networks and Genetic Algorithms). Starting from the state estimation, a given set of mathematical indices is computed to represent a snapshot of the current electric system operating point. The numerical values are then translated into a set of symbolic and linguistic quantities that are manipulated through a set of logical connectives and Inference Methods provided by the mathematical logic. As a result, the Fuzzy Logic gives a MW measure of the distance from the collapse limit, a metric usually appreciated by system operators. The Fuzzy System has been built and optimized by using, as a test system, a detailed model of the EHV Italian transmission network connected to an equivalent of the UCTE network (about 1700 buses). (author)

  10. Pathogen Webs in Collapsing Honey Bee Colonies

    Science.gov (United States)

    Cornman, R. Scott; Tarpy, David R.; Chen, Yanping; Jeffreys, Lacey; Lopez, Dawn; Pettis, Jeffery S.; vanEngelsdorp, Dennis; Evans, Jay D.

    2012-01-01

    Recent losses in honey bee colonies are unusual in their severity, geographical distribution, and, in some cases, failure to present recognized characteristics of known disease. Domesticated honey bees face numerous pests and pathogens, tempting hypotheses that colony collapses arise from exposure to new or resurgent pathogens. Here we explore the incidence and abundance of currently known honey bee pathogens in colonies suffering from Colony Collapse Disorder (CCD), otherwise weak colonies, and strong colonies from across the United States. Although pathogen identities differed between the eastern and western United States, there was a greater incidence and abundance of pathogens in CCD colonies. Pathogen loads were highly covariant in CCD but not control hives, suggesting that CCD colonies rapidly become susceptible to a diverse set of pathogens, or that co-infections can act synergistically to produce the rapid depletion of workers that characterizes the disorder. We also tested workers from a CCD-free apiary to confirm that significant positive correlations among pathogen loads can develop at the level of individual bees and not merely as a secondary effect of CCD. This observation and other recent data highlight pathogen interactions as important components of bee disease. Finally, we used deep RNA sequencing to further characterize microbial diversity in CCD and non-CCD hives. We identified novel strains of the recently described Lake Sinai viruses (LSV) and found evidence of a shift in gut bacterial composition that may be a biomarker of CCD. The results are discussed with respect to host-parasite interactions and other environmental stressors of honey bees. PMID:22927991

  11. Pathogen webs in collapsing honey bee colonies.

    Directory of Open Access Journals (Sweden)

    R Scott Cornman

    Full Text Available Recent losses in honey bee colonies are unusual in their severity, geographical distribution, and, in some cases, failure to present recognized characteristics of known disease. Domesticated honey bees face numerous pests and pathogens, tempting hypotheses that colony collapses arise from exposure to new or resurgent pathogens. Here we explore the incidence and abundance of currently known honey bee pathogens in colonies suffering from Colony Collapse Disorder (CCD, otherwise weak colonies, and strong colonies from across the United States. Although pathogen identities differed between the eastern and western United States, there was a greater incidence and abundance of pathogens in CCD colonies. Pathogen loads were highly covariant in CCD but not control hives, suggesting that CCD colonies rapidly become susceptible to a diverse set of pathogens, or that co-infections can act synergistically to produce the rapid depletion of workers that characterizes the disorder. We also tested workers from a CCD-free apiary to confirm that significant positive correlations among pathogen loads can develop at the level of individual bees and not merely as a secondary effect of CCD. This observation and other recent data highlight pathogen interactions as important components of bee disease. Finally, we used deep RNA sequencing to further characterize microbial diversity in CCD and non-CCD hives. We identified novel strains of the recently described Lake Sinai viruses (LSV and found evidence of a shift in gut bacterial composition that may be a biomarker of CCD. The results are discussed with respect to host-parasite interactions and other environmental stressors of honey bees.

  12. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.

  13. Meeting Environmental Requirements after a Bridge Collapse

    Science.gov (United States)

    2008-08-01

    This report is intended to assist transportation and environmental professionals in the event of a bridge collapse or similar emergency. It analyzes the environmental review process in five cases of bridge reconstruction following collapse in Florida...

  14. Perelman's collapsing theorem for 3-manifolds

    OpenAIRE

    Cao, Jianguo; Ge, Jian

    2009-01-01

    We will simplify the earlier proofs of Perelman's collapsing theorem of 3-manifolds given by Shioya-Yamaguchi and Morgan-Tian. Among other things, we use Perelman's semi-convex analysis of distance functions to construct the desired local Seifert fibration structure on collapsed 3-manifolds. The verification of Perelman's collapsing theorem is the last step of Perelman's proof of Thurston's Geometrization Conjecture on the classification of 3-manifolds. Our proof of Perelman's collapsing theo...

  15. Reusable collapsible impact energy absorber

    Energy Technology Data Exchange (ETDEWEB)

    Alghamdi, A.A.A. [Dept. of Mechanical Engineering, King Abdulaziz Univ., Jeddah (Saudi Arabia)

    2003-07-01

    In this paper experimental study of plastic deformation of aluminum frusta when reinverted is presented. Effects of changing the angle of frustum as well as frustum wall thickness on the absorbed energy are investigated. The details of the experimental plastic inversion and reinversion are given. Obtained results show that it is possible to use the inverted aluminum frusta several times, thus they are reusable collapsible absorbers. (orig.)

  16. Bubble-induced cave collapse.

    Science.gov (United States)

    Girihagama, Lakshika; Nof, Doron; Hancock, Cathrine

    2015-01-01

    Conventional wisdom among cave divers is that submerged caves in aquifers, such as in Florida or the Yucatan, are unstable due to their ever-growing size from limestone dissolution in water. Cave divers occasionally noted partial cave collapses occurring while they were in the cave, attributing this to their unintentional (and frowned upon) physical contact with the cave walls or the aforementioned "natural" instability of the cave. Here, we suggest that these cave collapses do not necessarily result from cave instability or contacts with walls, but rather from divers bubbles rising to the ceiling and reducing the buoyancy acting on isolated ceiling rocks. Using familiar theories for the strength of flat and arched (un-cracked) beams, we first show that the flat ceiling of a submerged limestone cave can have a horizontal expanse of 63 meters. This is much broader than that of most submerged Florida caves (~ 10 m). Similarly, we show that an arched cave roof can have a still larger expanse of 240 meters, again implying that Florida caves are structurally stable. Using familiar bubble dynamics, fluid dynamics of bubble-induced flows, and accustomed diving practices, we show that a group of 1-3 divers submerged below a loosely connected ceiling rock will quickly trigger it to fall causing a "collapse". We then present a set of qualitative laboratory experiments illustrating such a collapse in a circular laboratory cave (i.e., a cave with a circular cross section), with concave and convex ceilings. In these experiments, a metal ball represented the rock (attached to the cave ceiling with a magnet), and the bubbles were produced using a syringe located at the cave floor.

  17. Collapse models and perceptual processes

    Science.gov (United States)

    Carlo Ghirardi, Gian; Romano, Raffaele

    2014-04-01

    Theories including a collapse mechanism have been presented various years ago. They are based on a modification of standard quantum mechanics in which nonlinear and stochastic terms are added to the evolution equation. Their principal merits derive from the fact that they are mathematically precise schemes accounting, on the basis of a unique universal dynamical principle, both for the quantum behavior of microscopic systems as well as for the reduction associated to measurement processes and for the classical behavior of macroscopic objects. Since such theories qualify themselves not as new interpretations but as modifications of the standard theory they can be, in principle, tested against quantum mechanics. Recently, various investigations identifying possible crucial test have been discussed. In spite of the extreme difficulty to perform such tests it seems that recent technological developments allow at least to put precise limits on the parameters characterizing the modifications of the evolution equation. Here we will simply mention some of the recent investigations in this direction, while we will mainly concentrate our attention to the way in which collapse theories account for definite perceptual process. The differences between the case of reductions induced by perceptions and those related to measurement procedures by means of standard macroscopic devices will be discussed. On this basis, we suggest a precise experimental test of collapse theories involving conscious observers. We make plausible, by discussing in detail a toy model, that the modified dynamics can give rise to quite small but systematic errors in the visual perceptual process.

  18. DNA strand breaks in the lymphocytes of workers exposed to diisocyanates: indications of individual differences in susceptibility after low-dose and short-term exposure.

    Science.gov (United States)

    Marczynski, B; Merget, R; Mensing, T; Rabstein, S; Kappler, M; Bracht, A; Haufs, M G; Käfferlein, H U; Brüning, T

    2005-06-01

    Diisocyanates are chemically reactive and induce asthma, but data on genotoxic effects of diisocyanates in humans are limited. The investigation presented here used short term diisocyanate chamber exposure to study DNA strand breaks in lymphocytes of 10 healthy individuals and of 42 workers, with airway symptoms, who had previously been exposed to diisocyanates. The alkaline version of the Comet assay was used to analyse DNA strand breaks in lymphocytes. In addition, blood samples of 10 further control individuals without any exposure to diisocyanates were studied. Substances studied were 4,4'-methylenediphenyldiisocyanate (MDI, n=25), 2,4-toluenediisocynate and 2,6-toluenediisocyanate (TDI, n=5), and 1,6-hexamethylenediisocyanate (HDI, n=12), at concentrations between 5 and 30 ppb for 2 h. Lymphocytes isolated from the subjects before exposure and 30 min and 19 h after were used to evaluate DNA damage. No significant changes in DNA strand-break frequencies were measured, as Olive tail moment (OTM), either between groups or before and after diisocyanate exposure. OTM was similar in subjects with an asthmatic reaction (MDI, n=5; TDI, n=1; HDI, n=1) and in subjects without such a reaction. However, a small and susceptible group (about 10% of the individuals studied) could be identified with higher frequencies of DNA strand breaks in lymphocytes after chamber exposure. The occurrence of DNA damage in this group may be based on indirect mechanisms such as oxidative stress or apoptosis.

  19. Collapse of the balloon-expandable stent in the common iliac artery due to minor external compression in a lean patient

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Eun; Choi, Ho Cheol; Choi, Dae Seob; Lee, Sang Min; Lee, Jung Eun [Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju (Korea, Republic of); Cho, Su Beom; Ahn, Jong Hwa [Gyeongsang National University School of Medicine and Gyeongsang National University Changwon Hospital, Changwon (Korea, Republic of)

    2017-08-15

    A 60-year-old lean man with claudication due to severe stenosis of the right common iliac artery (CIA) underwent balloon-expandable stent deployment. Nineteen months later, claudication and lower limb ischemia in the patient recurred after minor external pressure and computed tomography indicated collapse of the right CIA stent. We performed balloon angioplasty again and self-expandable stent deployment was performed, and the patient's symptoms were relieved. We suggest that the CIA in a lean person could be susceptible to external pressure.

  20. HIERARCHICAL GRAVITATIONAL FRAGMENTATION. I. COLLAPSING CORES WITHIN COLLAPSING CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Naranjo-Romero, Raúl; Vázquez-Semadeni, Enrique; Loughnane, Robert M. [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 3-72, Morelia, Michoacán, 58089, México (Mexico)

    2015-11-20

    We investigate the Hierarchical Gravitational Fragmentation scenario through numerical simulations of the prestellar stages of the collapse of a marginally gravitationally unstable isothermal sphere immersed in a strongly gravitationally unstable, uniform background medium. The core developes a Bonnor–Ebert (BE)-like density profile, while at the time of singularity (the protostar) formation the envelope approaches a singular-isothermal-sphere (SIS)-like r{sup −2} density profile. However, these structures are never hydrostatic. In this case, the central flat region is characterized by an infall speed, while the envelope is characterized by a uniform speed. This implies that the hydrostatic SIS initial condition leading to Shu's classical inside-out solution is not expected to occur, and therefore neither should the inside-out solution. Instead, the solution collapses from the outside-in, naturally explaining the observation of extended infall velocities. The core, defined by the radius at which it merges with the background, has a time-variable mass, and evolves along the locus of the ensemble of observed prestellar cores in a plot of M/M{sub BE} versus M, where M is the core's mass and M{sub BE} is the critical BE mass, spanning the range from the “stable” to the “unstable” regimes, even though it is collapsing at all times. We conclude that the presence of an unstable background allows a core to evolve dynamically from the time when it first appears, even when it resembles a pressure-confined, stable BE-sphere. The core can be thought of as a ram-pressure confined BE-sphere, with an increasing mass due to the accretion from the unstable background.

  1. Enhancing mechanical behaviors of collapsible soil using two biopolymers

    Directory of Open Access Journals (Sweden)

    Mohamed Ayeldeen

    2017-04-01

    Full Text Available This study aims to investigate the possibility of using biopolymer (environmental friendly material to enhance the mechanical behaviors of collapsible soil. Two types of biopolymers were (xanthan gum and guar gum used in this study due to their stable behaviors under severe conditions and their availability with reasonable prices. The experimental program focused on three major soil properties, i.e. compaction characterizations, collapsible potential and shear parameters. These three properties are essential in process of soil improvement. Different biopolymer concentrations were used in this study and the experimental program was performed at two curing periods (soon after mixing the soil with the biopolymer and after one week curing time. Shear parameters were measured for the treated specimens under both soaked and unsoaked conditions, while a collapsible potential test was performed under different mixing conditions (wet mix and dry mix. A numerical model was built to predict the behavior of the treated collapsible soil after and before water immersing. The results indicated that the ability of both xanthan gum and guar gum can be used as improvement materials for collapsible soil treatment. The collapsible potential has been reduced from 9% to 1% after mixing the soil with 2% biopolymer concentration in the wet case. After one week curing, the cohesion has been increased from 8.5 kPa to 105 kPa by increasing the xanthan gum concentration from zero to 2%, leading to an overall improvement in soil shear strength. It also proves that the guar gum is superior to the xanthan gum. The shear strength of soil can be increased by about 30% when using the guar gum in comparison with the xanthan gum at the same conditions; however, the collapsible potential of soil material will be reduced by about 20%.

  2. Visualization during Stick-Release and Plateau Responses of Collapsed DNA

    Science.gov (United States)

    Ishida, R.; Murayama, Y.; Sano, M.

    We have observed the elastic response of single DNA molecules and visualized it during the collapsing transition induced by trivalent cation, spermidine (SPD). A fluorescent dye, YOYO-1, was used for the visualization. While the contour length of DNA increases as the YOYO concentration increases, the contour length decreases as SPD concentration increases. This indicates that YOYO-SPD exchange occurs on the single DNA molecule. We have observed bright spots in the fluorescence intensity profile of collapsed DNA during stretching, which may correspond to the collapsed parts within the single DNA. The decrease of the intensity of the spots in stretching implies the mechanical unfolding of collapsed parts.

  3. Spin wave collapse and incommensurate fluctuations in URu2Si2

    DEFF Research Database (Denmark)

    Buyers, W.J.L.; Tun, Z.; Petersen, T.

    1994-01-01

    To test if the T(N) = 17.7 K transition in URu2Si2 is driven by a divergence of a magnetic order parameter we performed high-resolution neutron scattering. At the ordering wave vector the spin-wave energy collapsed. and the susceptibility diverged as T(N) was approached. This confirms...

  4. Collapse Analysis of Timber Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Sørensen, John Dalsgaard

    2008-01-01

    A probabilistic based collapse analysis has been performed for a glulam frame structure supporting the roof over the main court in a Norwegian sports centre. The robustness analysis is based on the framework for robustness analysis introduced in the Danish Code of Practice for the Safety of Struc......A probabilistic based collapse analysis has been performed for a glulam frame structure supporting the roof over the main court in a Norwegian sports centre. The robustness analysis is based on the framework for robustness analysis introduced in the Danish Code of Practice for the Safety...... of Structures and a probabilistic modelling of the timber material proposed in the Probabilistic Model Code (PMC) of the Joint Committee on Structural Safety (JCSS). Due to the framework in the Danish Code the timber structure has to be evaluated with respect to the following criteria where at least one shall...... be fulfilled: a) demonstrating that those parts of the structure essential for the safety only have little sensitivity with respect to unintentional loads and defects, or b) demonstrating a load case with „removal of a limited part of the structure‟ in order to document that an extensive failure...

  5. Collapsible Cryogenic Storage Vessel Project

    Science.gov (United States)

    Fleming, David C.

    2002-01-01

    Collapsible cryogenic storage vessels may be useful for future space exploration missions by providing long-term storage capability using a lightweight system that can be compactly packaged for launch. Previous development efforts have identified an 'inflatable' concept as most promising. In the inflatable tank concept, the cryogen is contained within a flexible pressure wall comprised of a flexible bladder to contain the cryogen and a fabric reinforcement layer for structural strength. A flexible, high-performance insulation jacket surrounds the vessel. The weight of the tank and the cryogen is supported by rigid support structures. This design concept is developed through physical testing of a scaled pressure wall, and through development of tests for a flexible Layered Composite Insulation (LCI) insulation jacket. A demonstration pressure wall is fabricated using Spectra fabric for reinforcement, and burst tested under noncryogenic conditions. An insulation test specimens is prepared to demonstrate the effectiveness of the insulation when subject to folding effects, and to examine the effect of compression of the insulation under compressive loading to simulate the pressure effect in a nonrigid insulation blanket under the action atmospheric pressure, such as would be seen in application on the surface of Mars. Although pressure testing did not meet the design goals, the concept shows promise for the design. The testing program provides direction for future development of the collapsible cryogenic vessel concept.

  6. Sharper criteria for the wave collapse

    DEFF Research Database (Denmark)

    Kuznetsov, E.A.; Juul Rasmussen, J.; Rypdal, K.

    1995-01-01

    Sharper criteria for three-dimensional wave collapse described by the Nonlinear Schrodinger Equation (NLSE) are derived. The collapse threshold corresponds to the ground state soliton which is known to be unstable. Thus, for nonprefocusing distributions this represents the separatrix between...... collapsing and noncollapsing sectors. Numerical results support the theoretical results. Generalizations of the criteria for the NLSE with arbitrary power nonlinearity are also presented....

  7. Marginalization and Collapsibility in Graphical Interaction Models

    OpenAIRE

    Frydenberg, Morten

    1990-01-01

    The behaviour of a graphical interaction model under marginalization is discussed. A graphical interaction model is called collapsible onto a set of variables if the class of marginal distributions is the same as that implied by the related subgraph. The necessary and sufficient condition for collapsibility is found and it is shown that collapsibility is equivalent to a range of other important statistical properties of the model.

  8. Geophysical Processes - MO 2013 Collapse Potential (SHP)

    Data.gov (United States)

    NSGIC State | GIS Inventory — Collapse potential correlates with locations of underground mines and sinkholes. Computer-generated hazard calculations include areas in close proximity to mines and...

  9. Constructing black hole entropy from gravitational collapse

    CERN Document Server

    Acquaviva, Giovanni; Goswami, Rituparno; Hamid, Aymen I M

    2016-01-01

    Based on a recent proposal for the gravitational entropy of free gravitational fields, we investigate the thermodynamic properties of black hole formation through gravitational collapse in the framework of the semitetrad 1+1+2 covariant formalism. In the simplest case of an Oppenheimer-Snyder-Datt collapse we prove that the change in gravitational entropy outside a collapsing body is related to the variation of the surface area of the body itself, even before the formation of horizons. As a result, we are able to relate the Bekenstein-Hawking entropy of the black hole endstate to the variation of the vacuum gravitational entropy outside the collapsing body.

  10. Constructing black hole entropy from gravitational collapse

    CERN Document Server

    Acquaviva, Giovanni; Goswami, Rituparno; Hamid, Aymen I M

    2014-01-01

    Based on a recent proposal for the gravitational entropy of free gravitational fields, we investigate the thermodynamic properties of black hole formation through gravitational collapse in the framework of the semitetrad 1+1+2 covariant formalism. In the simplest case of an Oppenheimer-Snyder-Datt collapse we prove that the change in gravitational entropy outside a collapsing body is related to the variation of the surface area of the body itself, even before the formation of horizons. As a result, we are able to relate the Bekenstein-Hawking entropy of the black hole endstate to the variation of the vacuum gravitational entropy outside the collapsing body.

  11. Quantum radiation from quantum gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Vachaspati, Tanmay [Institute for Advanced Study, Princeton, NJ 08540 (United States); CERCA, Department of Physics, Case Western Reserve University, Cleveland, OH 44106-7079 (United States); Stojkovic, Dejan [HEPCOS, Department of Physics, SUNY at Buffalo, Buffalo, NY 14260-1500 (United States); CERCA, Department of Physics, Case Western Reserve University, Cleveland, OH 44106-7079 (United States)], E-mail: ds77@buffalo.edu

    2008-05-15

    We study quantum radiation emitted during the collapse of a quantized, gravitating, spherical domain wall. The amount of radiation emitted during collapse now depends on the wavefunction of the collapsing wall and the background spacetime. If the wavefunction is initially in the form of a sharp wavepacket, the expectation value of the particle occupation number is determined as a function of time and frequency. The results are in good agreement with our earlier semiclassical analysis and show that the quantum radiation is non-thermal and evaporation accompanies gravitational collapse.

  12. Quantum radiation from quantum gravitational collapse

    Science.gov (United States)

    Vachaspati, Tanmay; Stojkovic, Dejan

    2008-05-01

    We study quantum radiation emitted during the collapse of a quantized, gravitating, spherical domain wall. The amount of radiation emitted during collapse now depends on the wavefunction of the collapsing wall and the background spacetime. If the wavefunction is initially in the form of a sharp wavepacket, the expectation value of the particle occupation number is determined as a function of time and frequency. The results are in good agreement with our earlier semiclassical analysis and show that the quantum radiation is non-thermal and evaporation accompanies gravitational collapse.

  13. Collapse of granular media subjected to wetting

    Directory of Open Access Journals (Sweden)

    El Korchi Fatima Zahra

    2017-01-01

    Full Text Available This paper focuses on the collapse of granular materials subjected to wetting action. For soils, the collapse potential depends on several parameters such as liquid limit, matric suction, compactness, initial water content and the amount of fine particles. The effect of grain size, which plays a key role in the rearrangement of grains, remains little studied and poorly understood. To investigate the capillary origin of the collapse phenomenon, we present an experimental study on macroscopic and local scales. Our results show the effect of grain size and water content on collapse.

  14. Collapse of a Bose gas: Kinetic approach

    Indian Academy of Sciences (India)

    The stability and collapse of the Bose–Einstein condensates with negative scattering lengths have already been observed in the clouds of ultracold 7Li [2] and 85Rb [3] for temperatures (T) close to zero or well below the condensation point (Tc). Soon after the observation, many theories for the collapse have been proposed ...

  15. Gravitational collapse: The story so far

    Indian Academy of Sciences (India)

    Then we have the formation of a black hole in the universe as a result of the gravitational collapse. On the other hand, if the formation of event horizon gets delayed sufficiently during the collapse, the result is the development of a naked singularity, or a visible fire ball, which can possibly send out massive radiations to ...

  16. Collapse of Electrostatic Waves in Magnetoplasmas

    DEFF Research Database (Denmark)

    Shukla, P. K.; Yu, M. Y.; Juul Rasmussen, Jens

    1984-01-01

    The two-fluid model is employed to investigate the collapse of electrostatic waves in magnetized plasmas. It is found that nonlinear interaction of ion cyclotron, upper-, and lower-hybrid waves with adiabatic particle motion along the external magnetic field can cause wave-field collapse....

  17. Plastic collapse load of corroded steel plates

    Indian Academy of Sciences (India)

    Keywords. Corroded steel plate; plastic collapse; FEM; rough surface. ... The main aim of present work is to study plastic collapse load of corroded steel plates with irregular surfaces under tension. Non-linear finite element method ... Department of Ocean Engineering, AmirKabir University of Technology, 15914 Tehran, Iran ...

  18. Collapse of UOE manufactured steel pipes

    NARCIS (Netherlands)

    Gresnigt, A.M.; Foeken, R.J. van; Chen, S.

    2000-01-01

    The manufacturing method (seamless, UO, UOE) has a con-siderable influence on the collapse pressure of steel pipes. For UOE manufactured pipe, a significant reduction in collapse strength has been observed compared to not expanded pipe. A research program has been carried out to investigate the

  19. The Core-Collapse Supernova Explosion Mechanism

    Science.gov (United States)

    Müller, Bernhard

    2017-11-01

    The explosion mechanism of core-collapse supernovae is a long-standing problem in stellar astrophysics. We briefly outline the main contenders for a solution and review recent efforts to model core-collapse supernova explosions by means of multi-dimensional simulations. Focusing on the neutrino-driven mechanism, we summarize currents efforts to predict supernova explosion and remnant properties.

  20. The Collapse of the 'Celtic Tiger' Narrative

    DEFF Research Database (Denmark)

    Böss, Michael

    2011-01-01

    An account of the factors that led to the collapse of the 'Celtic Tiger' economy in 2008 and an explanation of the political effects and implications for Irish identity.......An account of the factors that led to the collapse of the 'Celtic Tiger' economy in 2008 and an explanation of the political effects and implications for Irish identity....

  1. The widespread collapse of an invasive species: Argentine ants (Linepithema humile) in New Zealand

    OpenAIRE

    Cooling, Meghan; Hartley, Stephen; Sim, Dalice A.; Lester, Philip J.

    2011-01-01

    Synergies between invasive species and climate change are widely considered to be a major biodiversity threat. However, invasive species are also hypothesized to be susceptible to population collapse, as we demonstrate for a globally important invasive species in New Zealand. We observed Argentine ant populations to have collapsed in 40 per cent of surveyed sites. Populations had a mean survival time of 14.1 years (95% CI = 12.9–15.3 years). Resident ant communities had recovered or partly re...

  2. An elastocapillary model of wood-fibre collapse.

    Science.gov (United States)

    Akbari, Amir; Hill, Reghan J; van de Ven, Theo G M

    2015-07-08

    An elastocapillary model for drying-induced collapse is proposed. We consider a circular elastic membrane with a hole at the centre that is deformed by the capillary pressure of simply and doubly connected menisci. The membrane overlays a cylindrical cavity with rigid walls, trapping a prescribed volume of water. This geometry may be suitable for studying structural failures and stiction in micro-electromechanical systems during wet etching, where capillary surfaces experience catastrophic transitions. The dry state is determined using the dihedral-angle and volume-turning-point stability criteria. Open and collapsed conformations are predicted from the scaled hole radius, cavity aspect ratio, meniscus contact angle with the membrane and cavity walls, and an elastocapillary number measuring the membrane stretching rigidity relative to the water surface tension. For a given scaled hole radius and cavity aspect ratio, there is a critical elastocapillary number above which the system does not collapse upon drying. The critical elastocapillary number is weakly influenced by the contact angle over a wide range of the scaled hole radius, thus indicating a limitation of surface hydrophobization for controlling the dry-state conformation. The model is applied to the drying of wood fibres above the fibre saturation point, determining the conditions leading to collapse.

  3. Small, Lightweight, Collapsible Glove Box

    Science.gov (United States)

    James, Jerry

    2009-01-01

    A small, lightweight, collapsible glove box enables its user to perform small experiments and other tasks. Originally intended for use aboard a space shuttle or the International Space Station (ISS), this glove box could also be attractive for use on Earth in settings in which work space or storage space is severely limited and, possibly, in which it is desirable to minimize weight. The development of this glove box was prompted by the findings that in the original space-shuttle or ISS setting, (1) it was necessary to perform small experiments in a large general-purpose work station, so that, in effect, they occupied excessive space; and it took excessive amounts of time to set up small experiments. The design of the glove box reflects the need to minimize the space occupied by experiments and the time needed to set up experiments, plus the requirement to limit the launch weight of the box and the space needed to store the box during transport into orbit. To prepare the glove box for use, the astronaut or other user has merely to insert hands through the two fabric glove ports in the side walls of the box and move two hinges to a locking vertical position (see figure). The user could do this while seated with the glove box on the user fs lap. When stowed, the glove box is flat and has approximately the thickness of two pieces of 8-in. (.20 cm) polycarbonate.

  4. Collapsed Lung: MedlinePlus Health Topic

    Science.gov (United States)

    ... Spanish Pneumothorax - infants (Medical Encyclopedia) Also in Spanish Topic Image MedlinePlus Email Updates Get Collapsed Lung updates ... Lung surgery Pneumothorax - slideshow Pneumothorax - infants Related Health Topics Chest Injuries and Disorders Lung Diseases Pleural Disorders ...

  5. Simple Analytic Models of Gravitational Collapse

    Energy Technology Data Exchange (ETDEWEB)

    Adler, R.

    2005-02-09

    Most general relativity textbooks devote considerable space to the simplest example of a black hole containing a singularity, the Schwarzschild geometry. However only a few discuss the dynamical process of gravitational collapse, by which black holes and singularities form. We present here two types of analytic models for this process, which we believe are the simplest available; the first involves collapsing spherical shells of light, analyzed mainly in Eddington-Finkelstein coordinates; the second involves collapsing spheres filled with a perfect fluid, analyzed mainly in Painleve-Gullstrand coordinates. Our main goal is pedagogical simplicity and algebraic completeness, but we also present some results that we believe are new, such as the collapse of a light shell in Kruskal-Szekeres coordinates.

  6. Detailed Jet Dynamics in a Collapsing Bubble

    Science.gov (United States)

    Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Farhat, Mohamed

    2015-12-01

    We present detailed visualizations of the micro-jet forming inside an aspherically collapsing cavitation bubble near a free surface. The high-quality visualizations of large and strongly deformed bubbles disclose so far unseen features of the dynamics inside the bubble, such as a mushroom-like flattened jet-tip, crown formation and micro-droplets. We also find that jetting near a free surface reduces the collapse time relative to the Rayleigh time.

  7. Anti-de Sitter gravitational collapse

    CERN Document Server

    Husain, V; Preston, B; Birukou, M

    2003-01-01

    We describe a formalism for studying spherically symmetric collapse of the massless scalar field in any spacetime dimension, and for any value of the cosmological constant LAMBDA. The formalism is used for numerical simulations of gravitational collapse in four spacetime dimensions with negative LAMBDA. We observe critical behaviour at the onset of black-hole formation, and find that the critical exponent is independent of LAMBDA. (letter to the editor)

  8. Lobar collapse with respiratory syncytial virus pneumonitis

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, S.F.; Erickson, S.; Oshman, D.; Hayden, F.

    1985-05-01

    In a study of 30 children with uncomplicated respiratory syncytial virus (RSV) pneumonias, a high incidence of lobar collapse (8/30-26%) was noted. This involved the right upper lobe in seven patients and the left upper lobe in one patient. It is probably attributable to anatomical predispositions, sloughing of necrotic epithelium, and stimulation of mucus production. Lobar collapse should be considered part of the spectrum of RSV pneumonitis.

  9. Environmental consequences of the Retsof Salt Mine roof collapse

    Science.gov (United States)

    Yager, Richard M.

    2013-01-01

    In 1994, the largest salt mine in North America, which had been in operation for more than 100 years, catastrophically flooded when the mine ceiling collapsed. In addition to causing the loss of the mine and the mineral resources it provided, this event formed sinkholes, caused widespread subsidence to land, caused structures to crack and subside, and changed stream flow and erosion patterns. Subsequent flooding of the mine drained overlying aquifers, changed the groundwater salinity distribution (rendering domestic wells unusable), and allowed locally present natural gas to enter dwellings through water wells. Investigations including exploratory drilling, hydrologic and water-quality monitoring, geologic and geophysical studies, and numerical simulation of groundwater flow, salinity, and subsidence have been effective tools in understanding the environmental consequences of the mine collapse and informing decisions about management of those consequences for the future. Salt mines are generally dry, but are susceptible to leaks and can become flooded if groundwater from overlying aquifers or surface water finds a way downward into the mined cavity through hundreds of feet of rock. With its potential to flood the entire mine cavity, groundwater is a constant source of concern for mine operators. The problem is compounded by the viscous nature of salt and the fact that salt mines commonly lie beneath water-bearing aquifers. Salt (for example halite or potash) deforms and “creeps” into the mined openings over time spans that range from years to centuries. This movement of salt can destabilize the overlying rock layers and lead to their eventual sagging and collapse, creating permeable pathways for leakage of water and depressions or openings at land surface, such as sinkholes. Salt is also highly soluble in water; therefore, whenever water begins to flow into a salt mine, the channels through which it flows increase in diameter as the surrounding salt dissolves

  10. Fishing amplifies forage fish population collapses.

    Science.gov (United States)

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches.

  11. Growth, collapse, and self-organized criticality in complex networks

    Science.gov (United States)

    Wang, Yafeng; Fan, Huawei; Lin, Weijie; Lai, Ying-Cheng; Wang, Xingang

    2016-04-01

    Network growth is ubiquitous in nature (e.g., biological networks) and technological systems (e.g., modern infrastructures). To understand how certain dynamical behaviors can or cannot persist as the underlying network grows is a problem of increasing importance in complex dynamical systems as well as sustainability science and engineering. We address the question of whether a complex network of nonlinear oscillators can maintain its synchronization stability as it expands. We find that a large scale avalanche over the entire network can be triggered in the sense that the individual nodal dynamics diverges from the synchronous state in a cascading manner within a relatively short time period. In particular, after an initial stage of linear growth, the network typically evolves into a critical state where the addition of a single new node can cause a group of nodes to lose synchronization, leading to synchronization collapse for the entire network. A statistical analysis reveals that the collapse size is approximately algebraically distributed, indicating the emergence of self-organized criticality. We demonstrate the generality of the phenomenon of synchronization collapse using a variety of complex network models, and uncover the underlying dynamical mechanism through an eigenvector analysis.

  12. Robustness Assessment of RC Framed Structures against Progressive Collapse

    Science.gov (United States)

    Ventura, Antonio; Chiaia, Bernardino; De Biagi, Valerio

    2017-10-01

    The structural behaviour of buildings under overloading or extraordinary events like impacts, explosions or human errors is extensively admitted to be an influential feature of structural design. Structural robustness is a requirement provided by many current design codes. However, the problem is often recognized in a qualitative manner without referring to a specific process for the evaluation or the achievement of the robustness of constructions. In this paper, a novel procedure derived from dynamic and non-linear static analyses is provided for evaluating and comparing the relative robustness of reinforced concrete (RC) frame buildings against progressive collapse. The developed methodology offers a formal way to compute “robustness curves” following the sudden loss of one or more vertical load carrying member/s. This method suggests a strategy for the definition of the robustness indices, which are applied to two RC frame buildings. The first building was designed for gravity load and earthquake resistance in accordance with Eurocode 8 and the second was the same structure, modified according to the tie force (TF) method. The TF method is one of the major design quantitative procedures for enhancing resistance to progressive collapse and it is currently recommended by the codes of practice. In an attempt to demonstrate the suitability of the procedure, the structural robustness and resistance to progressive collapse of the two schemes is compared.

  13. Simulations of protostellar collapse using multigroup radiation hydrodynamics. II. The second collapse

    DEFF Research Database (Denmark)

    Vaytet, N.; Chabrier, G.; Audit, E.

    2013-01-01

    Star formation begins with the gravitational collapse of a dense core inside a molecular cloud. As the collapse progresses, the centre of the core begins to heat up as it becomes optically thick. The temperature and density in the centre eventually reach high enough values where fusion reactions...... and dust opacities present large variations as a function of frequency. In this paper, we follow-up on a previous paper on the collapse and formation of Larson's first core using multigroup radiation hydrodynamics (Paper I) by extending the calculations to the second phase of the collapse and the formation...... of Larson's second core. We have made the use of a non-ideal gas equation of state as well as an extensive set of spectral opacities in a spherically symmetric fully implicit Godunov code to model all the phases of the collapse of a 0.1, 1 and 10 solar mass cloud cores. We find that, for a same central...

  14. Progressive Collapse of High-Rise Buildings from Fire

    Directory of Open Access Journals (Sweden)

    Pershakov Valerii

    2016-01-01

    Full Text Available Considers ensuring the stability of structures of high-rise buildings against progressive collapse due to fire, proposed measures to ensure the stability of high-rise buildings due to progressive collapse. The analysis of large fires in high-rise buildings with progressive collapse and review of the literature on the issue of progressive collapse. The analysis of the Ukrainian normative documents on progressive collapse resistance.

  15. Uncertainties in Core Collapse Supernovae Simulations

    Science.gov (United States)

    Duggan, Jefferson; Cunningham, J.; Kuhlmann, S.; Biswas, R.; Kovacs, E.; Spinka, H.

    2013-01-01

    We present the results of a study of selection criteria to identify Type Ia supernovae photometrically in a simulated mixed sample of Type Ia supernovae and core collapse supernovae. The simulated sample is a mockup of the expected results of the Dark Energy Survey (DES) using the supernovae simulation and fitting package of SNANA [Kessler et al. arXiv:0908.4280]. This is an extension of a previous analysis, [Gjergo et al. arXiv:1205.1480], with updated core collapse templates that are used to simulate the supernovae. We have also studied how systematic variations in the input parameters of the core collapse supernovae, such as absolute brightness and brightness smearing, affect the measured purity of the Type Ia supernova sample.

  16. Inflationary gravitational waves in collapse scheme models

    Directory of Open Access Journals (Sweden)

    Mauro Mariani

    2016-01-01

    Full Text Available The inflationary paradigm is an important cornerstone of the concordance cosmological model. However, standard inflation cannot fully address the transition from an early homogeneous and isotropic stage, to another one lacking such symmetries corresponding to our present universe. In previous works, a self-induced collapse of the wave function has been suggested as the missing ingredient of inflation. Most of the analysis regarding the collapse hypothesis has been solely focused on the characteristics of the spectrum associated to scalar perturbations, and within a semiclassical gravity framework. In this Letter, working in terms of a joint metric-matter quantization for inflation, we calculate, for the first time, the tensor power spectrum and the tensor-to-scalar ratio corresponding to the amplitude of primordial gravitational waves resulting from considering a generic self-induced collapse.

  17. Anterior chamber collapse syndrome in a koala.

    Science.gov (United States)

    Liddle, Vl; Naranjo, C; Bernays, Me

    2014-05-01

    Anterior chamber collapse syndrome has been recognised in various species and is associated with early-life ocular disease or trauma. It is important to differentiate this acquired condition from a congenital malformation. An adult female koala (Phascolarctos cinereus) was referred for assessment of buphthalmos and severe keratitis of the right eye. The degree of keratitis obstructed examination of intraocular structures. Enucleation of the affected eye was performed and the histopathological diagnosis was anterior chamber collapse syndrome and secondary glaucoma. This case contributes to the limited information available in the literature on anterior chamber collapse syndrome, a disease unique in having secondary glaucoma with minimal or no inflammation. The case also expands the literature available on ocular disease in koalas. More specifically, this is the only reported case of glaucoma, of any aetiology, in the koala. © 2014 Australian Veterinary Association.

  18. Inflationary gravitational waves in collapse scheme models

    Energy Technology Data Exchange (ETDEWEB)

    Mariani, Mauro, E-mail: mariani@carina.fcaglp.unlp.edu.ar [Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata (Argentina); Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); León, Gabriel, E-mail: gleon@df.uba.ar [Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria – Pab. I, 1428 Buenos Aires (Argentina)

    2016-01-10

    The inflationary paradigm is an important cornerstone of the concordance cosmological model. However, standard inflation cannot fully address the transition from an early homogeneous and isotropic stage, to another one lacking such symmetries corresponding to our present universe. In previous works, a self-induced collapse of the wave function has been suggested as the missing ingredient of inflation. Most of the analysis regarding the collapse hypothesis has been solely focused on the characteristics of the spectrum associated to scalar perturbations, and within a semiclassical gravity framework. In this Letter, working in terms of a joint metric-matter quantization for inflation, we calculate, for the first time, the tensor power spectrum and the tensor-to-scalar ratio corresponding to the amplitude of primordial gravitational waves resulting from considering a generic self-induced collapse.

  19. Unfolding Dynamics of Single Collapsed DNA Molecules

    Science.gov (United States)

    Murayama, Y.; Wada, H.; Ishida, R.; Sano, M.

    We observed elastic responses of single DNA molecules and visualized them during the collapsing transition induced by trivalent cation, spermidine (SPD). The force-extension curves show worm-like behavior, force plateau, and stick-release responses depending on SPD concentration. The periodic stick-release responses may reflect the unraveling of toroidal condensates. At much higher SPD concentration, we observed re-elongation of a single collapsed DNA. For the visualization, a fluorescent dye, YOYO, was used. We observed bright spots in the fluorescence intensity profile of a collapsed DNA during stretching, which may correspond to the collapsed parts within the single DNA. The decrease of the intensity of the spots in stretching implies the mechanical unfolding of collapsed parts. Towards achieving a microscopic understanding of these experimental results, we also investigate the elastic properties of a highly charged polyelectrolyte (PE) chain by Brownian dynamics simulation method. In our dynamic simulation, a PE has a small intrinsic stiffness (i.e., the PE is semiflexible) to model the stiffness of DNA chain, and added multivalent counterions are explicitly taken into account. As the electrostatic coupling parameter (proportional to counterion valency) is increased, counterion condensation is observed, leading finally to the PE collapse through the discontinuous transition for a sufficiently large coupling parameter. Mechanical unfolding of a PE globule reveals its molecular elasticities including force plateau, in agreement with the experimental observations. A numerically deduced electrostatic condensation energy is compared to the experimental value. Charge ordering in the PE-counterion complex and its deformation by the external forcing are elucidated in conjunction with the PE elastic responses. Other dynamic effects such as the effect of a pulling speed are also discussed.

  20. Role of evaporation in gravitational collapse

    CERN Document Server

    Baccetti, Valentina; Terno, Daniel R

    2016-01-01

    We study collapse of evaporating thin dust shells using two families of metrics to describe the {exterior geometry: the outgoing Vaidya metric and the retarded Schwarzschild metric. Both allow incorporation of Page's evaporation law (the latter in terms of the time at infinity), resulting in a modified equation} of motion for the shell. In these scenarios we find in each case that the collapse is accelerated due to evaporation, but the Schwarzschild radius is not crossed. Instead the shell is always at a certain sub-Planckian distance from this would-be horizon that depends only on the mass and evaporation rate.

  1. Slower recovery in space before collapse of connected populations.

    Science.gov (United States)

    Dai, Lei; Korolev, Kirill S; Gore, Jeff

    2013-04-18

    Slower recovery from perturbations near a tipping point and its indirect signatures in fluctuation patterns have been suggested to foreshadow catastrophes in a wide variety of systems. Recent studies of populations in the field and in the laboratory have used time-series data to confirm some of the theoretically predicted early warning indicators, such as an increase in recovery time or in the size and timescale of fluctuations. However, the predictive power of temporal warning signals is limited by the demand for long-term observations. Large-scale spatial data are more accessible, but the performance of warning signals in spatially extended systems needs to be examined empirically. Here we use spatially extended yeast populations, an experimental system with a fold bifurcation (tipping point), to evaluate early warning signals based on spatio-temporal fluctuations and to identify a novel spatial warning indicator. We found that two leading indicators based on fluctuations increased before collapse of connected populations; however, the magnitudes of the increases were smaller than those observed in isolated populations, possibly because local variation is reduced by dispersal. Furthermore, we propose a generic indicator based on deterministic spatial patterns, which we call 'recovery length'. As the spatial counterpart of recovery time, recovery length is the distance necessary for connected populations to recover from spatial perturbations. In our experiments, recovery length increased substantially before population collapse, suggesting that the spatial scale of recovery can provide a superior warning signal before tipping points in spatially extended systems.

  2. Gravitational collapse with decaying vacuum energy

    Indian Academy of Sciences (India)

    Abstract. The effect of dark energy on the end state of spherical radiation collapse is considered within the context of the cosmic censorship hypothesis. It is found that it is possible to have both black holes as well as naked singularities.

  3. Gravitational collapse with decaying vacuum energy

    Indian Academy of Sciences (India)

    β, showing that both naked singularities as well as black holes can form. The case α = 0.125, β = 0 yields a quadratic equation which corresponds to Vaidya collapse [8]. In general, for each value of α in the cubic, there corresponds a range of values of β which yield both positive and negative roots. For example, for α = 0.1, if.

  4. Identification and behavior of collapsible soils.

    Science.gov (United States)

    2011-01-01

    Loess is a soil that can exhibit large deformations upon wetting. Cases of wetting induced collapse in loess have : been documented for natural deposits and man-made fills. These issues are of concern to the Indiana DOT due to the growth : of the sta...

  5. Measurements and von Neumann projection/collapse

    Indian Academy of Sciences (India)

    unwanted superpositions of (system + apparatus)-states can be shown to be suppressed, leading eventually to the projection/collapse rule postulated in von Neumann's treatment of measurements [3]. In the next section, the measurement problem in quantum mechanics (QM) is recalled. In §3, some proposed improvements ...

  6. LISA pathfinder appreciably constrains collapse models

    Science.gov (United States)

    Helou, Bassam; Slagmolen, B. J. J.; McClelland, David E.; Chen, Yanbei

    2017-04-01

    Spontaneous collapse models are phenomological theories formulated to address major difficulties in macroscopic quantum mechanics. We place significant bounds on the parameters of the leading collapse models, the continuous spontaneous localization (CSL) model, and the Diosi-Penrose (DP) model, by using LISA Pathfinder's measurement, at a record accuracy, of the relative acceleration noise between two free-falling macroscopic test masses. In particular, we bound the CSL collapse rate to be at most (2.96 ±0.12 ) ×10-8 s-1 . This competitive bound explores a new frequency regime, 0.7 to 20 mHz, and overlaps with the lower bound 10-8 ±2 s-1 proposed by Adler in order for the CSL collapse noise to be substantial enough to explain the phenomenology of quantum measurement. Moreover, we bound the regularization cutoff scale used in the DP model to prevent divergences to be at least 40.1 ±0.5 fm , which is larger than the size of any nucleus. Thus, we rule out the DP model if the cutoff is the size of a fundamental particle.

  7. Granular Eruptions: Void Collapse and Jet Formation

    NARCIS (Netherlands)

    Mikkelsen, R.; Versluis, Andreas Michel; Koene, Elmer; Bruggert, Gert-Wim; van der Meer, Roger M.; van der Weele, J.P.; Lohse, Detlef

    2002-01-01

    Upon impact, sand is blown away in all directions, forming a splash. The ball digs a cylindrical void in the sand and the jet is formed when this void collapses: The focused sand pressure pushes the jet straight up into the air. When the jet comes down again, it breaks up into fragments, i.e.,

  8. Black hole free energy during charged collapse

    Science.gov (United States)

    Edery, Ariel; Beauchesne, Hugues

    2012-03-01

    Numerical work on gravitational collapse in isotropic coordinates has recently shown that the negative of the gravitational Lagrangian approaches the (Helmholtz) free energy of a Schwarzschild black hole at late times of the collapse. We investigate numerically this association during the collapse of a charged scalar field to a Reissner-Nordström (RN) black hole in isotropic coordinates. Charged collapse yields a large outgoing matter wave in the exterior region but this has a negligible effect on the interior. The thermodynamics via the free energy can therefore be investigated by focusing on the interior. We find that the percentage discrepancy between the numerical value for the Lagrangian and the analytical expression for the free energy reach values as low as 3% depending on the initial state. As a consistency check, we also implement a procedure for prolonging the evolution of the exterior region. The matter Lagrangian approaches zero everywhere (interior and exterior) showing clearly that the entropy of the charged black hole is gravitational in origin.

  9. Fire-induced collapses of steel structures

    DEFF Research Database (Denmark)

    Dondera, Alexandru; Giuliani, Luisa

    Single-story steel buildings such as car parks and industrial halls are often characterised by stiff beams and flexible columns and may experience an outward (sway) collapse during a fire, endangering people and properties outside the building. It is therefore a current interest of the research t...

  10. Collapse of wave function and special relativity

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Rosevaldo de [Universidade Federal do Mato Grosso (UFMT), MT (Brazil); Yoshida, Alexandre Calzavara [Universidade Federal de Uberlandia, MG (Brazil)

    2011-07-01

    Full text: In this work we show that for no incompatibility between Quantum Physics and Special Relativity, necessarily more postulates should be includes in Quantum Physics. What we want to show is that there is no inconsistency between collapse instantaneous of one entangled state with special relativity. We discovered the necessity to include one more postulate into Quantum Physics when we are studying entangled states in different reference systems. When we perform a Lorentz transformation into one entangled system, we realized that we need to make one more choice. This choice was not predicted by quantum physics nor by special relativity. Other options are: 1. if we define a privileged reference system where the collapse is instantaneous only in it, we will be back to the old discussion about the ether. I do not think that is a very interesting option, but I confess that it would also be an experimental question. 2. one could also define that the collapse was not simultaneous any reference system. 3. postulate: the collapse of the states is simultaneous to the observer carrying out the measure on the state. Adding one more postulate that we do not know if it is true or not, we can make Quantum Mechanics and Special Relativity consistently. An assumption has validity when has no inconsistency with the theories and is known to be proved experimentally. So the question about the validity of the postulates should be an experimental question. (author)

  11. The heterogeneity of world trade collapses

    NARCIS (Netherlands)

    P.A.G. van Bergeijk (Peter)

    2015-01-01

    textabstractThis paper analyses drivers of imports during the major world trade collapses of the Great Depression (1930s; 34 countries) and the Great Recession (1930s; 173 countries). The analysis deals with the first year of these episodes and develops a small empirical model that shows a

  12. Spherically symmetric inhomogeneous dust collapse in higher ...

    Indian Academy of Sciences (India)

    Higher dimensional space-time; naked singularity; cosmic censorship. PACS Nos 04.20.Dw; 04.50. ... The existence of strong curvature naked singularities in gravitational collapse of spherically symmetric space-times ..... distributions (in an appropriate metric space) can be discussed along the lines of [16]. 3. Strength of the ...

  13. Collapsing spherical null shells in general relativity

    Directory of Open Access Journals (Sweden)

    S Khakshournia

    2011-03-01

    Full Text Available In this work, the gravitational collapse of a spherically symmetric null shell with the flat interior and a charged Vaidya exterior spacetimes is studied. There is no gravitational impulsive wave present on the null hypersurface which is shear-free and contracting. It follows that there is a critical radius at which the shell bounces and starts expanding.

  14. Thin-Walled CFST Columns for Enhancing Seismic Collapse Performance of High-Rise Steel Frames

    Directory of Open Access Journals (Sweden)

    Yongtao Bai

    2017-01-01

    Full Text Available This paper numerically studied the collapse capacity of high-rise steel moment-resisting frames (SMRFs using various width-to-thickness members subjected to successive earthquakes. It was found that the long-period component of earthquakes obviously correlates with the first-mode period of high-rises controlled by the total number of stories. A higher building tends to produce more significant component deterioration to enlarge the maximum story drift angle at lower stories. The width-to-thickness ratio of beam and column components overtly affects the collapse capacity when the plastic deformation extensively develops. The ratio of residual to maximum story drift angle is significantly sensitive to the collapse capacity of various building models. A thin-walled concrete filled steel tubular (CFST column is proposed as one efficient alternative to enhance the overall stiffness and deformation capacity of the high-rise SMRFs with fragile collapse performance. With the equivalent flexural stiffness, CFST-MRF buildings with thin-walled members demonstrate higher capacity to avoid collapse, and the greater collapse margin indicates that CFST-MRFs are a reasonable system for high-rises in seismic prone regions.

  15. Is intrathoracic tracheal collapsibility correlated to clinical phenotypes and sex in patients with COPD?

    Directory of Open Access Journals (Sweden)

    Camiciottoli G

    2015-04-01

    are closely correlated. In patients with a predominant emphysematous phenotype, a reduced collapsibility may reflect the mechanical properties of the stiff hyperinflated emphysematous lung. The high collapsibility in patients with predominant airway disease, mild airway obstruction, and in women with this phenotype may reflect chronic airway inflammation. The lack of relationship with such symptoms as wheezing, cough, and dyspnea could indicate that intrathoracic tracheal collapsibility itself should be considered neither an abnormal feature of COPD nor a relevant clinical finding. Keywords: airway, computed tomography, lung density, pulmonary function, lung volumes

  16. Probabilistic Modeling of Landfill Subsidence Introduced by Buried Structure Collapse - 13229

    Energy Technology Data Exchange (ETDEWEB)

    Foye, Kevin; Soong, Te-Yang [CTI and Associates, Inc., 51331 W. Pontiac Trail, Wixom, MI 48393 (United States)

    2013-07-01

    The long-term reliability of land disposal facility final cover systems - and therefore the overall waste containment - depends on the distortions imposed on these systems by differential settlement/subsidence. The evaluation of differential settlement is challenging because of the heterogeneity of the waste mass and buried structure placement. Deterministic approaches to long-term final cover settlement prediction are not able to capture the spatial variability in the waste mass and sub-grade properties, especially discontinuous inclusions, which control differential settlement. An alternative is to use a probabilistic model to capture the non-uniform collapse of cover soils and buried structures and the subsequent effect of that collapse on the final cover system. Both techniques are applied to the problem of two side-by-side waste trenches with collapsible voids. The results show how this analytical technique can be used to connect a metric of final cover performance (inundation area) to the susceptibility of the sub-grade to collapse and the effective thickness of the cover soils. This approach allows designers to specify cover thickness, reinforcement, and slope to meet the demands imposed by the settlement of the underlying waste trenches. (authors)

  17. Unifying Research on Social-Ecological Resilience and Collapse.

    Science.gov (United States)

    Cumming, Graeme S; Peterson, Garry D

    2017-09-01

    Ecosystems influence human societies, leading people to manage ecosystems for human benefit. Poor environmental management can lead to reduced ecological resilience and social-ecological collapse. We review research on resilience and collapse across different systems and propose a unifying social-ecological framework based on (i) a clear definition of system identity; (ii) the use of quantitative thresholds to define collapse; (iii) relating collapse processes to system structure; and (iv) explicit comparison of alternative hypotheses and models of collapse. Analysis of 17 representative cases identified 14 mechanisms, in five classes, that explain social-ecological collapse. System structure influences the kind of collapse a system may experience. Mechanistic theories of collapse that unite structure and process can make fundamental contributions to solving global environmental problems. Copyright © 2017. Published by Elsevier Ltd.

  18. Dynamic control of collapse in a vortex Airy beam.

    Science.gov (United States)

    Chen, Rui-Pin; Chew, Khian-Hooi; He, Sailing

    2013-01-01

    Here we study systematically the self-focusing dynamics and collapse of vortex Airy optical beams in a Kerr medium. The collapse is suppressed compared to a non-vortex Airy beam in a Kerr medium due to the existence of vortex fields. The locations of collapse depend sensitively on the initial power, vortex order, and modulation parameters. The collapse may occur in a position where the initial field is nearly zero, while no collapse appears in the region where the initial field is mainly distributed. Compared with a non-vortex Airy beam, the collapse of a vortex Airy beam can occur at a position away from the area of the initial field distribution. Our study shows the possibility of controlling and manipulating the collapse, especially the precise position of collapse, by purposely choosing appropriate initial power, vortex order or modulation parameters of a vortex Airy beam.

  19. Gravitational and electric energies in collapse of spherically thin capacitor

    CERN Document Server

    Ruffini, Remo

    2013-01-01

    In our previous article (PHYSICAL REVIEW D 86, 084004 (2012)), we present a study of strong oscillating electric fields and electron-positron pair-production in gravitational collapse of a neutral stellar core at or over nuclear densities. In order to understand the back-reaction of such electric energy building and radiating on collapse, we adopt a simplified model describing the collapse of a spherically thin capacitor to give an analytical description how gravitational energy is converted to both kinetic and electric energies in collapse. It is shown that (i) averaged kinetic and electric energies are the same order, about an half of gravitational energy of spherically thin capacitor in collapse; (ii) caused by radiating and rebuilding electric energy, gravitational collapse undergoes a sequence of "on and off" hopping steps in the microscopic Compton scale. Although such a collapse process is still continuous in terms of macroscopic scales, it is slowed down as kinetic energy is reduced and collapsing tim...

  20. Observations on cyanobacterial population collapse in eutrophic lake water

    NARCIS (Netherlands)

    Gons, H.J.; Ebert, J.; Hoogveld, H.L.; Van den Hove, L.; Pel, R.; Takkenberg, W.; Woldringh, C.J.

    2002-01-01

    In two laboratory-scale enclosures of water from the shallow, eutrophic Lake Loosdrecht (the Netherlands), the predominating filamentous cyanobacteria grew vigorously for 2 weeks, but then their populations simultaneously collapsed, whereas coccoid cyanobacteria and algae persisted . The collapse

  1. Experimental observation of critical slowing down before population collapse

    Science.gov (United States)

    Dai, Lei; Vorselen, Daan; Dudley, Carmel; Ornek, Onur; Korolev, Kirill; Gore, Jeff

    2012-02-01

    Tipping points marking population collapse and other critical transitions in natural systems (e.g. ecosystems, the climate) can be described by a fold bifurcation in the dynamics of the system. Theory predicts that the approach of bifurcations will result in an increasingly slow recovery from small perturbations, a phenomenon called critical slowing down. Here we demonstrate the direct observation of critical slowing down before population collapse using replicate laboratory populations of the budding yeast Saccharomyces cerevisiae. We mapped the bifurcation diagram experimentally and found a significant increase in both the size and timescale of the fluctuations of population density near a fold bifurcation, in agreement with the theory. We further confirmed the utility of theoretically predicted warning signals by observing them in two different slowly deteriorating environments. To extend the application of warning signals to spatially extended populations, we proposed and identified several indicators based on the emergence of spatial patterns. Our results suggest that generic temporal and spatial indicators of critical slowing down can be useful in predicting tipping points in population dynamics.

  2. Females lead population collapse of the endangered Hawaii creeper.

    Directory of Open Access Journals (Sweden)

    Leonard A Freed

    Full Text Available Population collapses result from drastic environmental changes, but the sexes may differ in vulnerability. Collapse of the endangered Hawaii creeper (Oreomystis mana at Hakalau Forest National Wildlife Refuge resulted from food limitation associated with increased numbers of an introduced bird (Japanese white-eye, Zosterops japonicus, which competes with the creeper for food. Both creeper sexes had stunted bill growth and the greatest change in molt of native species in the community. With a surge in numbers of white-eyes, a recent cohort of adult females had very low survival after breeding, while adult males from the same cohort, and older females and males, continued to have high survival. Lower female survival resulted in a significantly more male-biased adult sex ratio. Recent low female survival was based on a great cost of reproduction, indicated by molt-breeding overlap that was previously avoided, and lower fat during the lengthy fledgling period. The difference in female survival between cohorts was associated with stunted bills from being reared in and then breeding in an increasingly poor food environment. Trend analysis of survey data indicate that the bird is declining throughout the refuge, with males being 72-80% of adults left six years after the white-eye increased. Competition over time was consistent with that previously documented over space on the Island of Hawaii. Adaptive management to recover the bird in this protected area needs to focus on improving both adult female survival and the adult sex ratio.

  3. Collapse and revival in holographic quenches

    Science.gov (United States)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2015-04-01

    We study holographic models related to global quantum quenches in finite size systems. The holographic set up describes naturally a CFT, which we consider on a circle and a sphere. The enhanced symmetry of the conformal group on the circle motivates us to compare the evolution in both cases. Depending on the initial conditions, the dual geometry exhibits oscillations that we holographically interpret as revivals of the initial field theory state. On the sphere, this only happens when the energy density created by the quench is small compared to the system size. However on the circle considerably larger energy densities are compatible with revivals. Two different timescales emerge in this latter case. A collapse time, when the system appears to have dephased, and the revival time, when after rephasing the initial state is partially recovered. The ratio of these two times depends upon the initial conditions in a similar way to what is observed in some experimental setups exhibiting collapse and revivals.

  4. Progenitors of Core-Collapse Supernovae

    Science.gov (United States)

    Hirschi, R.; Arnett, D.; Cristini, A.; Georgy, C.; Meakin, C.; Walkington, I.

    2017-02-01

    Massive stars have a strong impact on their surroundings, in particular when they produce a core-collapse supernova at the end of their evolution. In these proceedings, we review the general evolution of massive stars and their properties at collapse as well as the transition between massive and intermediate-mass stars. We also summarise the effects of metallicity and rotation. We then discuss some of the major uncertainties in the modelling of massive stars, with a particular emphasis on the treatment of convection in 1D stellar evolution codes. Finally, we present new 3D hydrodynamic simulations of convection in carbon burning and list key points to take from 3D hydrodynamic studies for the development of new prescriptions for convective boundary mixing in 1D stellar evolution codes.

  5. Collapsing dynamics of attractive Bose-Einstein condensates

    DEFF Research Database (Denmark)

    Bergé, L.; Juul Rasmussen, J.

    2002-01-01

    The self-similar collapse of 3D and quasi-2D atom condensates with negative scattering length is examined. 3D condensates are shown to blow up following the scenario of weak collapse, for which 3-body recombination weakly dissipates the atoms. In contrast, 2D condensates undergo a strong collapse...

  6. Simulated cytoskeletal collapse via tau degradation.

    Directory of Open Access Journals (Sweden)

    Austin Sendek

    Full Text Available We present a coarse-grained two dimensional mechanical model for the microtubule-tau bundles in neuronal axons in which we remove taus, as can happen in various neurodegenerative conditions such as Alzheimers disease, tauopathies, and chronic traumatic encephalopathy. Our simplified model includes (i taus modeled as entropic springs between microtubules, (ii removal of taus from the bundles due to phosphorylation, and (iii a possible depletion force between microtubules due to these dissociated phosphorylated taus. We equilibrate upon tau removal using steepest descent relaxation. In the absence of the depletion force, the transverse rigidity to radial compression of the bundles falls to zero at about 60% tau occupancy, in agreement with standard percolation theory results. However, with the attractive depletion force, spring removal leads to a first order collapse of the bundles over a wide range of tau occupancies for physiologically realizable conditions. While our simplest calculations assume a constant concentration of microtubule intercalants to mediate the depletion force, including a dependence that is linear in the detached taus yields the same collapse. Applying percolation theory to removal of taus at microtubule tips, which are likely to be the protective sites against dynamic instability, we argue that the microtubule instability can only obtain at low tau occupancy, from 0.06-0.30 depending upon the tau coordination at the microtubule tips. Hence, the collapse we discover is likely to be more robust over a wide range of tau occupancies than the dynamic instability. We suggest in vitro tests of our predicted collapse.

  7. Galactic collapse of scalar field dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Alcubierre, Miguel [Max-Planck-Institut fuer Gravitationsphysik, Am Muehlenberg 1, D-14476 Golm (Germany); Guzman, F Siddhartha [Max-Planck-Institut fuer Gravitationsphysik, Am Muehlenberg 1, D-14476 Golm (Germany); Matos, Tonatiuh [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, AP 14-740, 07000 Mexico, DF (Mexico); Nunez, Dario [Centre for Gravitational Physics and Geometry, Penn State University, University Park, PA 16802 (United States); Urena-Lopez, L Arturo [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, AP 14-740, 07000 Mexico, DF (Mexico); Wiederhold, Petra [Departamento de Control Automatico, Centro de Investigacion y de Estudios Avanzados del IPN, AP 14-740, 07000 Mexico, DF (Mexico)

    2002-10-07

    We present a scenario for core galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for the formation of a galactic core plus a remnant halo, which is in agreement with cosmological observations and phenomenological studies in galaxies.

  8. Adsorption-like Collapse of Diblock Copolymers

    OpenAIRE

    Orlandini, E.; Seno, F.; Stella, A. L.

    1999-01-01

    A linear copolymer made of two reciprocally attracting N-monomer blocks collapses to a compact phase through a novel transition, whose exponents are determined with extensive MC simulations in two and three dimensions. In the former case, an identification with the statistical geometry of suitable percolation paths allows to predict that the number of contacts between the blocks grows like $N^{9/16}$. In the compact phase the blocks are mixed and, in two dimensions, also zipped, in such a way...

  9. Ultrasonographic evaluation of tracheal collapse in dogs

    Science.gov (United States)

    Eom, Kidong; Moon, Kumjung; Seong, Yunsang; Oh, Taeho; Yi, Sungjoon; Lee, Keunwoo

    2008-01-01

    Tracheal ultrasonography was performed to measure the width of the tracheal ring shadow and to assess the clinical relevance of these measurements for identifying tracheal collapse. The first tracheal ring width (FTRW) and thoracic inlet tracheal ring width (TITRW) were measured on both expiration and inspiration. The mean of the FTRW width (129 dogs) was greater in expiration (10.97 ± 1.02 mm, p = 0.001) than that in inspiration (9.86 ± 1.03 mm). For 51 normal dogs, the mean of the TITRW width was greater in expiration (9.05 ± 1.52 mm, p = 0.001) than in inspiration (8.02 ± 1.43 mm). For 78 tracheal collapse dogs, the mean of the TITRW width was greater in expiration (15.89 ± 1.01 mm, p = 0.001) than in inspiration (14.85 ± 1.17 mm). The TITRW/FTRW ratio of the normal dogs was higher (p = 0.001) in expiration (0.81 ± 0.09) than that in inspiration (0.79 ± 0.10). When compared between the normal and tracheal collapse dogs, the TITRW/FTRW ratio was also increased (p = 0.001) both in expiration (1.54 ± 0.09) and inspiration (1.47 ± 0.08), respectively. Based on these results, the cutoff level of the TITRW/FTRW ratio was statistically analyzed according to the receiver operating characteristic curve and it could be set at 1.16 in expiration and at 1.13 in inspiration. We have demonstrated that tracheal ultrasonography is a useful technique for the evaluation of tracheal collapse and it can be a supportive tool together with the radiographic findings for making the correct diagnosis. PMID:19043316

  10. The Collapse of Ecosystem Engineer Populations

    Directory of Open Access Journals (Sweden)

    José F. Fontanari

    2018-01-01

    Full Text Available Humans are the ultimate ecosystem engineers who have profoundly transformed the world’s landscapes in order to enhance their survival. Somewhat paradoxically, however, sometimes the unforeseen effect of this ecosystem engineering is the very collapse of the population it intended to protect. Here we use a spatial version of a standard population dynamics model of ecosystem engineers to study the colonization of unexplored virgin territories by a small settlement of engineers. We find that during the expansion phase the population density reaches values much higher than those the environment can support in the equilibrium situation. When the colonization front reaches the boundary of the available space, the population density plunges sharply and attains its equilibrium value. The collapse takes place without warning and happens just after the population reaches its peak number. We conclude that overpopulation and the consequent collapse of an expanding population of ecosystem engineers is a natural consequence of the nonlinear feedback between the population and environment variables.

  11. Matter and gravitons in the gravitational collapse

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2016-12-01

    Full Text Available We consider the effects of gravitons in the collapse of baryonic matter that forms a black hole. We first note that the effective number of (soft off-shell gravitons that account for the (negative Newtonian potential energy generated by the baryons is conserved and always in agreement with Bekenstein's area law of black holes. Moreover, their (positive interaction energy reproduces the expected post-Newtonian correction and becomes of the order of the total ADM mass of the system when the size of the collapsing object approaches its gravitational radius. This result supports a scenario in which the gravitational collapse of regular baryonic matter produces a corpuscular black hole without central singularity, in which both gravitons and baryons are marginally bound and form a Bose–Einstein condensate at the critical point. The Hawking emission of baryons and gravitons is then described by the quantum depletion of the condensate and we show the two energy fluxes are comparable, albeit negligibly small on astrophysical scales.

  12. Matter and gravitons in the gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Casadio, Roberto, E-mail: casadio@bo.infn.it [Dipartimento di Fisica e Astronomia, Alma Mater Universià di Bologna, via Irnerio 46, 40126 Bologna (Italy); I.N.F.N., Sezione di Bologna, IS FLAG, viale B. Pichat 6/2, I-40127 Bologna (Italy); Giugno, Andrea, E-mail: A.Giugno@physik.uni-muenchen.de [Arnold Sommerfeld Center, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 München (Germany); Giusti, Andrea, E-mail: andrea.giusti@bo.infn.it [Dipartimento di Fisica e Astronomia, Alma Mater Universià di Bologna, via Irnerio 46, 40126 Bologna (Italy); I.N.F.N., Sezione di Bologna, IS FLAG, viale B. Pichat 6/2, I-40127 Bologna (Italy)

    2016-12-10

    We consider the effects of gravitons in the collapse of baryonic matter that forms a black hole. We first note that the effective number of (soft off-shell) gravitons that account for the (negative) Newtonian potential energy generated by the baryons is conserved and always in agreement with Bekenstein's area law of black holes. Moreover, their (positive) interaction energy reproduces the expected post-Newtonian correction and becomes of the order of the total ADM mass of the system when the size of the collapsing object approaches its gravitational radius. This result supports a scenario in which the gravitational collapse of regular baryonic matter produces a corpuscular black hole without central singularity, in which both gravitons and baryons are marginally bound and form a Bose–Einstein condensate at the critical point. The Hawking emission of baryons and gravitons is then described by the quantum depletion of the condensate and we show the two energy fluxes are comparable, albeit negligibly small on astrophysical scales.

  13. Essential ingredients in core-collapse supernovae

    Directory of Open Access Journals (Sweden)

    W. Raphael Hix

    2014-03-01

    Full Text Available Carrying 1044 joules of kinetic energy and a rich mix of newly synthesized atomic nuclei, core-collapse supernovae are the preeminent foundries of the nuclear species which make up our solar system and ourselves. Signaling the inevitable death of a massive star, and the birth of a neutron star or black hole, core-collapse supernovae combine physics over a wide range in spatial scales, from kilometer-sized hydrodynamic motions (eventually growing to gigameter scale down to femtometer-scale nuclear reactions. We will discuss our emerging understanding of the convectively-unstable, neutrino-driven explosion mechanism, based on increasingly realistic neutrino radiation hydrodynamic simulations that include progressively better nuclear and particle physics. Multi-dimensional models with spectral neutrino transport from several research groups, which slowly develop successful explosions for a range of progenitors, have recently motivated changes in our understanding of the neutrino reheating mechanism. In a similar fashion, improvements in nuclear physics, most notably explorations of weak interactions on nuclei and the nuclear equation of state, continue to refine our understanding of the births of neutron stars and the supernovae that result. Recent progress on both the macroscopic and microscopic effects that affect core-collapse supernovae are discussed.

  14. Collapse of tall granular columns in fluid

    Science.gov (United States)

    Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves

    2017-06-01

    Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.

  15. Novel vacuum conditions in inflationary collapse models

    Science.gov (United States)

    Bengochea, Gabriel R.; León, Gabriel

    2017-11-01

    Within the framework of inflationary models that incorporate a spontaneous reduction of the wave function for the emergence of the seeds of cosmic structure, we study the effects on the primordial scalar power spectrum by choosing a novel initial quantum state that characterizes the perturbations of the inflaton. Specifically, we investigate under which conditions one can recover an essentially scale free spectrum of primordial inhomogeneities when the standard Bunch-Davies vacuum is replaced by another one that minimizes the renormalized stress-energy tensor via a Hadamard procedure. We think that this new prescription for selecting the vacuum state is better suited for the self-induced collapse proposal than the traditional one in the semiclassical gravity picture. We show that the parametrization for the time of collapse, considered in previous works, is maintained. Also, we obtain an angular spectrum for the CMB temperature anisotropies consistent with the one that best fits the observational data. Therefore, we conclude that the collapse mechanism might be of a more fundamental character than previously suspected.

  16. Precombination Cloud Collapse and Baryonic Dark Matter

    Science.gov (United States)

    Hogan, Craig J.

    1993-01-01

    A simple spherical model of dense baryon clouds in the hot big bang 'strongly nonlinear primordial isocurvature baryon fluctuations' is reviewed and used to describe the dependence of cloud behavior on the model parameters, baryon mass, and initial over-density. Gravitational collapse of clouds before and during recombination is considered including radiation diffusion and trapping, remnant type and mass, and effects on linear large-scale fluctuation modes. Sufficiently dense clouds collapse early into black holes with a minimum mass of approx. 1 solar mass, which behave dynamically like collisionless cold dark matter. Clouds below a critical over-density, however, delay collapse until recombination, remaining until then dynamically coupled to the radiation like ordinary diffuse baryons, and possibly producing remnants of other kinds and lower mass. The mean density in either type of baryonic remnant is unconstrained by observed element abundances. However, mixed or unmixed spatial variations in abundance may survive in the diffuse baryon and produce observable departures from standard predictions.

  17. Magnetic susceptibilities of minerals

    Science.gov (United States)

    Rosenblum, Sam; Brownfield, I.K.

    2000-01-01

    Magnetic separation of minerals is a topic that is seldom reported in the literature for two reasons. First, separation data generally are byproducts of other projects; and second, this study requires a large amount of patience and is unusually tedious. Indeed, we suspect that most minerals probably are never investigated for this property. These data are timesaving for mineralogists who concentrate mono-mineralic fractions for chemical analysis, age dating, and for other purposes. The data can certainly be used in the ore-beneficiation industries. In some instances, magnetic-susceptibility data may help in mineral identification, where other information is insufficient. In past studies of magnetic separation of minerals, (Gaudin and Spedden, 1943; Tille and Kirkpatrick, 1956; Rosenblum, 1958; Rubinstein and others, 1958; Flinter, 1959; Hess, 1959; Baker, 1962; Meric and Peyre, 1963; Rojas and others, 1965; and Duchesne, 1966), the emphasis has been on the ferromagnetic and paramagnetic ranges of extraction. For readers interested in the history of magnetic separation of minerals, Krumbein and Pettijohn (1938, p. 344-346) indicated nine references back to 1848. The primary purpose of this paper is to report the magnetic-susceptibility data on as many minerals as possible, similar to tables of hardness, specific gravity, refractive indices, and other basic physical properties of minerals. A secondary purpose is to demonstrate that the total and best extraction ranges are influenced by the chemistry of the minerals. The following notes are offered to help avoid problems in separating a desired mineral concentrate from mixtures of mineral grains.

  18. Collapse and fragmentation of molecular cloud cores. 2: Collapse induced by stellar shock waves

    Science.gov (United States)

    Boss, Alan P.

    1995-01-01

    The standard scenario for low-mass star formation involves 'inside-out' collapse of a dense molecular cloud core following loss of magnetic field support through ambipolar diffusion. However, isotopic anomalies in presolar grains and meteoritical inclusions imply that the collapse of the presolar cloud may have been triggered by a stellar shock wave. This paper explores 'outside-in' collapse, that is, protostellar collapse initiated directly by the compression of quiescent dense cloud cores impacted by relatively slow stellar shock waves. A second-order accurate, gravitational hydrodynamics code has been used to study both the spherically symmetrical and three-dimensional evolution of initially centrally condensed, isothermal, self-gravitating, solar-mass cloud cores that are struck by stellar shock waves with velocities up to 25 km/s and postshock temperatures of 10 to 10,000 K. The models show that such mild shock waves do not completely shred and destroy the cloud, and that the dynamical ram pressure can compress the cloud to the verge of self-gravitational collapse. However, compression caused by a high postshock temperature is a considerably more effective means of inducing collapse. Shock-induced collapse produces high initial mass accretion rates (greater than 10(exp -4) solar mass/yr in a solar-mass cloud) that decline rapidly to much lower values, depending on the presence (approximately 10(exp -6) solar mass/yr) or absence (approximately 10(exp -8) to 10(exp -7) solar mass/yr) of an infinite reservoir of mass. Stellar mass accretion rates approximately 10(exp -7) solar mass/yr have been previously inferred from the luminosities of T Tauri stars; balanced mass accretion (stellar rate = envelope rate) at approximately 10(exp -7) solar mass/yr could then be possible if accretion occurs from a finite mass reservoir. Fluid tracers are used to determine what fraction of the stellar shock material is incorporated into the resulting protostellar object and disk

  19. Observation of Weak Collapse in a Bose-Einstein Condensate

    Directory of Open Access Journals (Sweden)

    Christoph Eigen

    2016-12-01

    Full Text Available We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterize the critical point for collapse and the collapse dynamics, observing universal behavior in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely, that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.

  20. Observation of Weak Collapse in a Bose-Einstein Condensate

    Science.gov (United States)

    Eigen, Christoph; Gaunt, Alexander L.; Suleymanzade, Aziza; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P.

    2016-10-01

    We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterize the critical point for collapse and the collapse dynamics, observing universal behavior in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely, that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.

  1. Shock-induced collapse of a bubble inside a deformable vessel

    Science.gov (United States)

    Coralic, Vedran; Colonius, Tim

    2013-01-01

    Shockwave lithotripsy repeatedly focuses shockwaves on kidney stones to induce their fracture, partially through cavitation erosion. A typical side effect of the procedure is hemorrhage, which is potentially the result of the growth and collapse of bubbles inside blood vessels. To identify the mechanisms by which shock-induced collapse could lead to the onset of injury, we study an idealized problem involving a preexisting bubble in a deformable vessel. We utilize a high-order accurate, shock- and interface-capturing, finite-volume scheme and simulate the three-dimensional shock-induced collapse of an air bubble immersed in a cylindrical water column which is embedded in a gelatin/water mixture. The mixture is a soft tissue simulant, 10% gelatin by weight, and is modeled by the stiffened gas equation of state. The bubble dynamics of this model configuration are characterized by the collapse of the bubble and its subsequent jetting in the direction of the propagation of the shockwave. The vessel wall, which is defined by the material interface between the water and gelatin/water mixture, is invaginated by the collapse and distended by the impact of the jet. The present results show that the highest measured pressures and deformations occur when the volumetric confinement of the bubble is strongest, the bubble is nearest the vessel wall and/or the angle of incidence of the shockwave reduces the distance between the jet tip and the nearest vessel surface. For a particular case considered, the 40 MPa shockwave utilized in this study to collapse the bubble generated a vessel wall pressure of almost 450 MPa and produced both an invagination and distention of nearly 50% of the initial vessel radius on a 𝒪(10) ns timescale. These results are indicative of the significant potential of shock-induced collapse to contribute to the injury of blood vessels in shockwave lithotripsy. PMID:24015027

  2. Simulations of protostellar collapse using multigroup radiation hydrodynamics. I. The first collapse

    DEFF Research Database (Denmark)

    Vaytet, Neil; Audit, Edouard; Chabrier, Gilles

    2012-01-01

    Radiative transfer plays a major role in the process of star formation. Many simulations of gravitational collapse of a cold gas cloud followed by the formation of a protostellar core use a grey treatment of radiative transfer coupled to the hydrodynamics. However, dust opacities which dominate...... the spherically symmetric collapse of a 1 solar mass cloud core. Monochromatic dust opacities for five different temperature ranges were used to compute Planck and Rosseland means inside each frequency group. The results are very consistent with previous studies and only small differences were observed between...... the grey and multigroup simulations. For a same central density, the multigroup simulations tend to produce first cores with a slightly higher radius and central temperature. We also performed simulations of the collapse of a 10 and 0.1 solar mass cloud, which showed the properties of the first core...

  3. Are fast radio bursts markers of dark core collapse?

    Science.gov (United States)

    Katz, J. I.

    2017-07-01

    Are some neutron stars produced without a supernova, without ejecting mass in a remnant? Theoretical calculations of core collapse in massive stars often predict this. The observation of the repeating FRB 121102, whose dispersion measure has not changed over several years, suggests that dark core collapses are not just failures of computer codes, but may be real. The existence of one repeating fast radio burst (FRB) with unchanging dispersion measure is not conclusive, but within a decade hundreds or thousands of FRB are expected to be discovered, likely including scores of repeaters, permitting useful statistical inferences. A naïve supernova remnant model predicts observable decline in dispersion measure for 100 yr after its formation. If an upper limit on the decline of 2 pc cm-3 yr-1 is set for five repeating FRBs, then the naïve model with nominal parameters is rejected at the 95 per cent level of confidence. This may indicate dark neutron star formation without a supernova or supernova remnant. This hypothesis may also be tested with the Large Synoptic Survey Telescope (LSST) data that would show, if present, a supernova at an interferometric FRB position if it occurred within the LSST epoch.

  4. Collapse of sodium polyacrylate chains in calcium salt solutions

    Science.gov (United States)

    Schweins, R.; Huber, K.

    The sodium salt of polyacrylic acid (NaPA) precipitates in the presence of Ca^{2+}-ions. This phase behaviour can be represented by a phase diagram where the critical NaPA concentration is plotted versus the critical Ca^{2+} concentration resulting in a straight line as a phase boundary. The location of this phase boundary is influenced by the presence of an inert monovalent salt like NaCl. The present contribution focuses on the coil dimensions of NaPA chains in dilute aqueous solution corresponding to the one phase region of such a phase diagram. A variety of parameters with which the size and shape of the polyelectrolyte chains can be modulated are revealed. Approaching the phase boundary by decreasing the NaPA concentration at a constant Ca^{2+} content leads to a collapse of the NaPA chains. Combined static and dynamic light scattering suggests a compact spherical shape as the final state of this transition, both in 0.1 M NaCl and in 0.01 M NaCl. In the lower NaCl concentration, indication is presented for the existence of a cigar or pearl necklace like intermediate. Most strikingly, the collapsed chains can be reexpanded by increasing the concentration of inert NaCl at constant content of NaPA and Ca^{2+}. Clearly, excessive Na+-ions displace the Ca^{2+}-ions from the NaPA chains.

  5. Nonstationary magnetosonic wave dynamics in plasmas exhibiting collapse

    Science.gov (United States)

    Chakrabarti, Nikhil; Maity, Chandan; Schamel, Hans

    2013-08-01

    In a Lagrangian fluid approach, an explicit method has been presented previously to obtain an exact nonstationary magnetosonic-type wave solution in compressible magnetized plasmas of arbitrary resistivity showing competition among hydrodynamic convection, magnetic field diffusion, and dispersion [Chakrabarti , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.145003 106, 145003 (2011)]. The purpose of the present work is twofold: it serves (i) to describe the physical and mathematical background of the involved magnetosonic wave dynamics in more detail, as proposed by our original Letter, and (ii) to present an alternative approach, which utilizes the Lagrangian mass variable as a new spatial coordinate [Schamel, Phys. Rep.PRPLCM0370-157310.1016/j.physrep.2003.12.002 392, 279 (2004)]. The obtained exact nonlinear wave solutions confirm the correctness of our previous results, indicating a collapse of the magnetic field irrespective of the presence of dispersion and resistivity. The mean plasma density, on the other hand, is less singular, showing collapse only when dispersive effects are negligible. These results may contribute to our understanding of the generation of strongly localized magnetic fields (and currents) in plasmas, and they are expected to be of special importance in the astrophysical context of magnetic star formation.

  6. Serum Leukocyte Immunoglobulin-Like Receptor A3 (LILRA3 Is Increased in Patients with Multiple Sclerosis and Is a Strong Independent Indicator of Disease Severity; 6.7kbp LILRA3 Gene Deletion Is Not Associated with Diseases Susceptibility.

    Directory of Open Access Journals (Sweden)

    Hongyan An

    Full Text Available Leukocyte immunoglobulin-like receptor A3 (LILRA3 is a soluble immune regulatory molecule primarily expressed by monocytes and macrophages. A homozygous 6.7kbp LILRA3 gene deletion that removes the first seven of its eight exons is predicted to lead to lack of LILRA3 protein, although this has not been experimentally confirmed. Moreover, there are conflicting results with regards to the link between the LILRA3 homozygous genetic deletion and susceptibility to multiple sclerosis (MS in different European populations. The aim of this study was to investigate whether LILRA3 gene deletion is associated with MS susceptibility in a North American cohort of European ancestry and assess if serum LILRA3 protein level is a marker of clinical subtype and/or disease severity in MS. A total of 456 patients with MS and 99 unrelated healthy controls were genotyped for the 6.7kbp LILRA3 gene deletion and levels of LILRA3 protein in sera determined by in-house sandwich ELISA. We showed that LILRA3 gene deletion was not associated with MS susceptibility and did not affect the age of disease onset, clinical subtype or disease severity. However, we discovered for the first time that homozygous LILRA3 gene deletion results in lack of production of LILRA3 protein. Importantly, LILRA3 protein level was significantly increased in sera of patients with MS when compared with control subjects, particularly in more severe type primary progressive MS. Multiple regression analysis showed that LILRA3 level in serum was one of the strongest independent markers of disease severity in MS, which potentially can be used as a diagnostic marker.

  7. Evaluation of collapse and non-collapse of parallel bridges affected by liquefaction and lateral spreading.

    OpenAIRE

    Turner, Benjamin; Brandenberg, Scott J.; Stewart, Jonathan P.

    2013-01-01

    An overview is presented of the authors’ ongoing investigation of the performance of a railroad bridge and adjacent highway bridge during the 2010 El Mayor-Cucapah earthquake in Baja California, Mexico. A span of the pile-supported railroad bridge collapsed due to movement of a pier from lateral spreading. The highway bridge, supported on drilled shafts, suffered moderate structural damage but did not collapse. An overview of the site, structural details of the bridges, and the proposed geote...

  8. Thermal and Chemical Evolution of Collapsing Filaments

    Energy Technology Data Exchange (ETDEWEB)

    Gray, William J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Scannapieco, Evan [Arizona State Univ., Mesa, AZ (United States). School of Earth and Space Exploration

    2013-01-15

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10-3Z filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253, but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  9. THERMAL AND CHEMICAL EVOLUTION OF COLLAPSING FILAMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Gray, William J. [Lawrence Livermore National Laboratory, P.O. Box 808, L-038, Livermore, CA 94550 (United States); Scannapieco, Evan [School of Earth and Space Exploration, Arizona State University, P.O. Box 871404, Tempe, AZ 85287-1494 (United States)

    2013-05-10

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z Almost-Equal-To 0.1 Z{sub Sun} filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form a dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10{sup -3} Z{sub Sun} filaments, the collapse proceeds much more slowly. This is mostly due to the lower initial temperatures, which lead to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbursting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occurs. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  10. Climate and the collapse of Maya civilization.

    Science.gov (United States)

    Haug, Gerald H; Günther, Detlef; Peterson, Larry C; Sigman, Daniel M; Hughen, Konrad A; Aeschlimann, Beat

    2003-03-14

    In the anoxic Cariaco Basin of the southern Caribbean, the bulk titanium content of undisturbed sediment reflects variations in riverine input and the hydrological cycle over northern tropical South America. A seasonally resolved record of titanium shows that the collapse of Maya civilization in the Terminal Classic Period occurred during an extended regional dry period, punctuated by more intense multiyear droughts centered at approximately 810, 860, and 910 A.D. These new data suggest that a century-scale decline in rainfall put a general strain on resources in the region, which was then exacerbated by abrupt drought events, contributing to the social stresses that led to the Maya demise.

  11. Climate change and the population collapse during the "Great Famine" in pre-industrial Europe.

    Science.gov (United States)

    Lima, Mauricio

    2014-02-01

    Population dynamics, economy, and human demography started with Malthus, the idea that population growth is limited by resources and "positive checks" occur when population growth overshoots the available resources. In fact, historical evidence indicates that long-term climate changes have destabilized civilizations and caused population collapses via food shortages, diseases, and wars. One of the worst population collapses of human societies occurred during the early fourteenth century in northern Europe; the "Great Famine" was the consequence of the dramatic effects of climate deterioration on human population growth. Thus, part of my motivation was to demonstrate that simple theoretical-based models can be helpful in understanding the causes of population change in preindustrial societies. Here, the results suggest that a logistic model with temperature as a "lateral" perturbation effect is the key element for explaining the population collapse exhibited by the European population during the "Great Famine".

  12. Nonlocal (but also nonsingular) physics at the last stages of gravitational collapse

    Science.gov (United States)

    Saini, Anshul; Stojkovic, Dejan

    2014-02-01

    We study the end stages of gravitational collapse of the thin shell of matter in ingoing Eddington-Finkelstein coordinates. We use the functional Schrodinger formalism to capture quantum effects in the near singularity limit. We find that the equations of motion which govern the behavior of the collapsing shell near the classical singularity become strongly nonlocal. This reinforces previous arguments that quantum gravity in the strong field regime might be nonlocal. We managed to solve the nonlocal equation of motion for the dust shell case, and found an explicit form of the wave function describing the collapsing shell. This wave function and the corresponding probability density are nonsingular at the origin, thus indicating that quantization should be able to rid gravity of singularities, just as was the case with the singular Coulomb potential.

  13. Characterization and quantification of path dependency in landslide susceptibility

    NARCIS (Netherlands)

    Samia, Jalal; Temme, Arnaud; Bregt, Arnold; Wallinga, Jakob; Guzzetti, Fausto; Ardizzone, Francesca; Rossi, Mauro

    2017-01-01

    Landslides cause major environmental damage, economic losses and casualties. Although susceptibility to landsliding is usually considered an exclusively location-specific phenomenon, indications exist that landslide history co-determines susceptibility to future landslides. In this contribution,

  14. Null fluid collapse in brane world models

    Science.gov (United States)

    Harko, Tiberiu; Lake, Matthew J.

    2014-03-01

    The brane world description of our Universe entails a large extra dimension and a fundamental scale of gravity that may be lower than the Planck scale by several orders of magnitude. An interesting consequence of this scenario occurs in the nature of spherically symmetric vacuum solutions to the brane gravitational field equations, which often have properties quite distinct from the standard black hole solutions of general relativity. In this paper, the spherically symmetric collapse on the brane world of four types of null fluid, governed by the barotropic, polytropic, strange quark "bag" model and Hagedorn equations of state, is investigated. In each case, we solve the approximate gravitational field equations, obtained in the high-density limit, determine the equation which governs the formation of apparent horizons and investigate the conditions for the formation of naked singularities. Though, naively, one would expect the increased effective energy density on the brane to favor the formation of black holes over naked singularities, we find that, for the types of fluid considered, this is not the case. However, the black hole solutions differ substantially from their general-relativistic counterparts and brane world corrections often play a role analogous to charge in general relativity. As an astrophysical application of this work, the possibility that energy emission from a Hagedorn fluid collapsing to form a naked singularity may be a source of GRBs in the brane world is also considered.

  15. Spherical collapse in νΛCDM

    Science.gov (United States)

    LoVerde, Marilena

    2014-10-01

    The abundance of massive dark matter halos hosting galaxy clusters provides an important test of the masses of relic neutrino species. The dominant effect of neutrino mass is to lower the typical amplitude of density perturbations that eventually form halos, but for neutrino masses ≳0.4 eV the threshold for halo formation can be changed significantly as well. We study the spherical collapse model for halo formation in cosmologies with neutrino masses in the range mνi=0.05-1 eV and find that halo formation is differently sensitive to Ων and mν. That is, different neutrino hierarchies with a common Ων are in principle distinguishable. The added sensitivity to mν is small but potentially important for scenarios with heavier sterile neutrinos. Massive neutrinos cause the evolution of density perturbations to be scale dependent at high redshift which complicates the usual mapping between the collapse threshold and halo abundance. We propose one way of handling this and compute the correction to the halo mass function within this framework. For ∑mνi≲0.3 eV, our prescription for the halo abundance is only ≲15% different than the standard calculation. However for larger neutrino masses the differences approach 50-100% which, if verified by simulations, could alter neutrino mass constraints from cluster abundance.

  16. Susceptibility Genes in Thyroid Autoimmunity

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Ban

    2005-01-01

    Full Text Available The autoimmune thyroid diseases (AITD are complex diseases which are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility in combination with external factors (e.g. dietary iodine is believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been employed to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions that are linked with AITD, and in some of these loci, putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD and Hashimoto's thyroiditis (HT and some are common to both the diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g. HLA, CTLA-4 and thyroid specific genes (e.g. TSHR, Tg. Most likely, these loci interact and their interactions may influence disease phenotype and severity.

  17. Kinematic fingerprint of core-collapsed globular clusters

    Science.gov (United States)

    Bianchini, P.; Webb, J. J.; Sills, A.; Vesperini, E.

    2018-01-01

    Dynamical evolution drives globular clusters toward core collapse, which strongly shapes their internal properties. Diagnostics of core collapse have so far been based on photometry only, namely on the study of the concentration of the density profiles. Here we present a new method to robustly identify core-collapsed clusters based on the study of their stellar kinematics. We introduce the kinematic concentration parameter, ck, the ratio between the global and local degree of energy equipartition reached by a cluster, and show through extensive direct N-body simulations that clusters approaching core collapse and in the post-core collapse phase are strictly characterized by ck > 1. The kinematic concentration provides a suitable diagnostic to identify core-collapsed clusters, independent from any other previous methods based on photometry. We also explore the effects of incomplete radial and stellar mass coverage on the calculation of ck and find that our method can be applied to state-of-art kinematic datasets.

  18. A simple proof of Perelman's collapsing theorem for 3-manifolds

    OpenAIRE

    Cao, Jianguo; Ge, Jian

    2010-01-01

    We will simplify earlier proofs of Perelman's collapsing theorem for 3-manifolds given by Shioya-Yamaguchi and Morgan-Tian. Among other things, we use Perelman's critical point theory (e.g., multiple conic singularity theory and his fibration theory) for Alexandrov spaces to construct the desired local Seifert fibration structure on collapsed 3-manifolds. The verification of Perelman's collapsing theorem is the last step of Perelman's proof of Thurston's Geometrization Conjecture on the class...

  19. Shell instability of a collapsing dense core

    Science.gov (United States)

    Ntormousi, Evangelia; Hennebelle, Patrick

    2015-02-01

    Aims: Understanding the formation of binary and multiple stellar systems largely comes down to studying the circumstances under which a condensing core fragments (or not) during the first stages of the collapse. However, both the probability of fragmentation and the number of fragments seem to be determined to a large degree by the initial conditions. In this work we explore this dependence by studying the fate of the linear perturbations of a homogeneous gas sphere, both analytically and numerically. Methods: In particular, we investigate the stability of the well-known homologous solution that describes the collapse of a uniform spherical cloud. One problem that arises in such treatments is the mathematical singularity in the perturbation equations, which corresponds to the location of the sonic point of the flow. This difficulty is surpassed here by explicitly introducing a weak shock next to the sonic point as a natural way of connecting the subsonic to the supersonic regimes. In parallel, we perform adaptive mesh refinement (AMR) numerical simulations of the linear stages of the collapse and compare the growth rates obtained by each method. Results: With this combination of analytical and numerical tools, we explore the behavior of both axisymmetric and non-axisymmetric perturbations. The numerical experiments provide the linear growth rates as a function of the core's initial virial parameter and as a function of the azimuthal wave number of the perturbation. The overlapping regime of the numerical experiments and the analytical predictions is the situation of a cold and large cloud, and in this regime the analytically calculated growth rates agree very well with the ones obtained from the simulations. Conclusions: The use of a weak shock as part of the perturbation allows us to find physically acceptable solutions to the equations for a continuous range of growth rates. The numerical simulations agree very well with the analytical prediction for the most

  20. Experimental bounds on collapse models from gravitational wave detectors

    Science.gov (United States)

    Carlesso, Matteo; Bassi, Angelo; Falferi, Paolo; Vinante, Andrea

    2016-12-01

    Wave function collapse models postulate a fundamental breakdown of the quantum superposition principle at the macroscale. Therefore, experimental tests of collapse models are also fundamental tests of quantum mechanics. Here, we compute the upper bounds on the collapse parameters, which can be inferred by the gravitational wave detectors LIGO, LISA Pathfinder, and AURIGA. We consider the most widely used collapse model, the continuous spontaneous localization (CSL) model. We show that these experiments exclude a huge portion of the CSL parameter space, the strongest bound being set by the recently launched space mission LISA Pathfinder. We also rule out a proposal for quantum-gravity-induced decoherence.

  1. Elevated dissolved organic carbon biodegradability from thawing and collapsing permafrost

    National Research Council Canada - National Science Library

    Abbott, Benjamin W; Larouche, Julia R; Jones, Jeremy B; Bowden, William B; Balser, Andrew W

    2014-01-01

    ...) in water flowing from collapsing permafrost (thermokarst) on the North Slope of Alaska and tested the role of DOC chemical composition and nutrient concentration in determining biodegradability...

  2. Patient selection for upper airway stimulation: is concentric collapse in sleep endoscopy predictable?

    Science.gov (United States)

    Steffen, Armin; Frenzel, Henning; Wollenberg, Barbara; König, Inke R

    2015-12-01

    Upper airway stimulation is an effective treatment option for obstructive sleep apnea after failure of positive airway pressure (PAP) therapy. To ensure a therapeutic effect, closed-loop hypoglossal nerve implants require the absence of palatal complete concentric collapse during sleep endoscopy. The frequency and potential predictors of this exclusion criterion are unknown. Over a 2-year period, 74 consecutive patients with sleep apnea who sought PAP alternatives were evaluated with sleep endoscopy using propofol. The influence of sleep apnea severity and anthropometric characteristics as predictors of sleep endoscopy results was investigated. One-fifth of all patients showed a concentric collapse. Gender and age did not predict the presence of concentric collapse, but higher body mass and apnea hypopnea index values were predictive (p = 0.011; e.g., 0.026). The most commonly used body mass index values for upper airway stimulation indications demonstrated acceptable specificity (BMI 32 kg/m(2) 0.71, 95 % confidence interval = 0.57, 0.82; e.g., 35 kg/m(2) 0.81, 95 % confidence interval = 0.69, 0.90). Despite the association with overweight, a significant number of severely overweight patients had no concentric palatal collapse. Concentric collapse is a somewhat common condition encountered in sleep endoscopy evaluations of PAP alternatives, and cannot be sustainably predicted with anthropometric or sleep assessments. Sleep surgeons should be aware of the possibility of concentric collapse, especially in candidates who are more overweight and have severe sleep apnea. Sleep endoscopy can be useful for providing information about continuous positive airway pressure (CPAP) alternatives or to motivate patient adherence to treatment.

  3. Final fate of charged anisotropic fluid collapse

    Science.gov (United States)

    Khan, Suhail; Shah, Hassan; Ahmad, Zahid; Ramzan, Muhammad

    2017-11-01

    This paper studies the effects of charge on spherically symmetric collapse of anisotropic fluid with a positive cosmological constant. It is observed that electromagnetic field places restriction on the bounds of cosmological constant, which acts as repulsive force against the contraction of matter content and hence the rate of destruction is faster in the presence of electromagnetic field. We have also noted that the presence of charge affects the time interval between the formation of cosmological horizon (CH) and black hole horizon (BHH). When the electric field strength E(t, r) vanishes, our investigations are in full agreement with the results obtained by Ahmad and Malik [Int. J. Theor. Phys. 55, 600 (2016)].

  4. Current collapse in tunneling transport through benzene.

    Science.gov (United States)

    Hettler, M H; Wenzel, W; Wegewijs, M R; Schoeller, H

    2003-02-21

    We investigate the electrical transport through a system of benzene coupled to metal electrodes by electron tunneling. Using electronic structure calculations, a semiquantitative model for the pi electrons of the benzene is derived that includes general two-body interactions. After exact diagonalization of the benzene model the transport is computed using perturbation theory for weak electrode-benzene coupling (golden rule approximation). We include the effect of an applied electric field on the molecular states, as well as radiative relaxation. We predict a current collapse and strong negative differential conductance due to a "blocking" state when the electrode is coupled to the para-position of benzene. In contrast, for coupling to the meta-position, a series of steps in the I-V curve is found.

  5. Collapse and bounce of null fluids

    CERN Document Server

    Creelman, Bradley

    2016-01-01

    Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inwards even when non-gravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this proposal for the more general Husain null fluids. We find that: 1) generically there is a thin shell discontinuity along the junction surface between ingoing and outgoing solutions, 2) there are special cases where the shell vanishes and 3) these conclusions also apply to charged Vaidya (the original paper argued that there were no shells at the junctions). Along the way we note an apparent error in the standard classification of energy condition violations for Type II stress-energy tensors.

  6. Inhomogeneities from quantum collapse scheme without inflation

    Directory of Open Access Journals (Sweden)

    Gabriel R. Bengochea

    2015-04-01

    Full Text Available In this work, we consider the problem of the emergence of seeds of cosmic structure in the framework of the non-inflationary model proposed by Hollands and Wald. In particular, we consider a modification to that proposal designed to account for breaking the symmetries of the initial quantum state, leading to the generation of the primordial inhomogeneities. This new ingredient is described in terms of a spontaneous reduction of the wave function. We investigate under which conditions one can recover an essentially scale free spectrum of primordial inhomogeneities, and which are the dominant deviations that arise in the model as a consequence of the introduction of the collapse of the quantum state into that scenario.

  7. Inhomogeneities from quantum collapse scheme without inflation

    CERN Document Server

    Bengochea, Gabriel R; Sudarsky, Daniel

    2015-01-01

    In this work, we consider the problem of the emergence of seeds of cosmic structure in the framework of the non-inflationary model proposed by Hollands and Wald. In particular, we consider a modification to that proposal designed to account for breaking the symmetries of the initial quantum state, leading to the generation of the primordial inhomogeneities. This new ingredient is described in terms of a spontaneous reduction of the wave function. We investigate under which conditions one can recover an essentially scale free spectrum of primordial inhomogeneities, and which are the dominant deviations that arise in the model as a consequence of the introduction of the collapse of the quantum state into that scenario.

  8. Magnetorotational Explosions of Core-Collapse Supernovae

    Directory of Open Access Journals (Sweden)

    Gennady S. Bisnovatyi-Kogan

    2014-12-01

    Full Text Available Core-collapse supernovae are accompanied by formation of neutron stars. The gravitation energy is transformed into the energy of the explosion, observed as SN II, SN Ib,c type supernovae. We present results of 2-D MHD simulations, where the source of energy is rotation, and magnetic eld serves as a "transition belt" for the transformation of the rotation energy into the energy of the explosion. The toroidal part of the magnetic energy initially grows linearly with time due to dierential rotation. When the twisted toroidal component strongly exceeds the poloidal eld, magneto-rotational instability develops, leading to a drastic acceleration in the growth of magnetic energy. Finally, a fast MHD shock is formed, producing a supernova explosion. Mildly collimated jet is produced for dipole-like type of the initial field. At very high initial magnetic field no MRI development was found.

  9. Inhomogeneities from quantum collapse scheme without inflation

    Energy Technology Data Exchange (ETDEWEB)

    Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Cañate, Pedro, E-mail: pedro.canate@nucleares.unam.mx [Instituto de Ciencias Nucleares, UNAM, México D.F. 04510, México (Mexico); Sudarsky, Daniel, E-mail: sudarsky@nucleares.unam.mx [Instituto de Ciencias Nucleares, UNAM, México D.F. 04510, México (Mexico)

    2015-04-09

    In this work, we consider the problem of the emergence of seeds of cosmic structure in the framework of the non-inflationary model proposed by Hollands and Wald. In particular, we consider a modification to that proposal designed to account for breaking the symmetries of the initial quantum state, leading to the generation of the primordial inhomogeneities. This new ingredient is described in terms of a spontaneous reduction of the wave function. We investigate under which conditions one can recover an essentially scale free spectrum of primordial inhomogeneities, and which are the dominant deviations that arise in the model as a consequence of the introduction of the collapse of the quantum state into that scenario.

  10. Collapse of Synchronization in a Memristive Network

    Science.gov (United States)

    Lü, Mi; Wang, Chun-Ni; Tang, Jun; Ma, Jun

    2015-12-01

    For an oscillating circuit or coupled circuits, damage in electric devices such as inductor, resistance, memristor even capacitor can cause breakdown or collapse of the circuits. These damage could be associated with external attack or aging in electric devices, and then the bifurcation parameters could be deformed from normal values. Resonators or signal generators are often synchronized to produce powerful signal series and this problem could be investigated by using synchronization in network. Complete synchronization could be induced by linear coupling in a two-dimensional network of identical oscillators when the coupling intensity is beyond certain threshold. The collective behavior and synchronization state are much dependent on the bifurcation parameters. Any slight fluctuation in parameter and breakdown in bifurcation parameter can cause transition of synchronization even collapse of synchronization in the network. In this paper, a two-dimensional network composed of the resonators coupled with memristors under nearest-neighbor connection is designed, and the network can reach complete synchronization by carefully selecting coupling intensity. The network keeps synchronization after certain transient period, then a bifurcation parameter in a resonator is switched from the previous value and the adjacent resonators (oscillators) are affected in random. It is found that the synchronization area could be invaded greatly in a diffusive way. The damage area size is much dependent on the selection of diffusive period of damage and deformation degree in the parameter. Indeed, the synchronization area could keep intact at largest size under intermediate deformation degree and coupling intensity. Supported by the National Natural Science of China under Grant Nos. 11265008 and 11365014

  11. An experience sampling study on the ecological validity of the SWN-20: Indication that subjective well-being is associated with momentary affective states above and beyond psychosis susceptibility.

    Science.gov (United States)

    Pos, Karin; de Wit, Iris E; van Dijk, Floor A; Bartels-Velthuis, Agna A; Bruggeman, Richard; Meijer, Carin J; de Haan, Lieuwe; Alizadeh, Berhooz Z; Bartels-Velthuis, Agna A; Van Beveren, Nico J; Bruggeman, Richard; Cahn, Wiepke; de Haan, Lieuwe; Delespaul, Phillipe; Meijer, Carin J; Myin-Germeys, Inez; Kahn, Rene S; Schirmbeck, Frederike; Simons, Claudia J P; van Haren, Neeltje E; van Os, Jim; van Winkel, Ruud

    2017-12-01

    Subjective well-being (SWB) is associated with treatment adherence and symptom outcome in people with psychotic disorders. Also, it is associated with psychosis susceptibility and it is partly hereditable. The SWN-20 is a widely used tool to assess subjective well-being in patients; it was also found to be suitable for assessing SWB in healthy populations. Yet it is unclear how this retrospectively measured construct may be associated with momentary affective state, which is the proposed underlying mechanism of subjective well-being. This study therefore investigated the ecological validity of the SWN-20 in people at different risk for psychosis. In 63 patients with a psychotic disorder and 61 siblings of patients with a psychotic disorder we assessed whether subjective well-being as measured with the SWN-20, was associated with momentary positive affect, negative affect, reward experience and stress-sensitivity as measured by the experience sample method (ESM). Higher subjective well-being was associated with higher momentary positive affect and lower negative affect, and this association was not conditional on psychosis vulnerability. Subjective well-being was not associated with stress-sensitivity or reward-experience. SWN-20 is an easy-to-use and ecologically valid tool to measure subjective well-being in people with different vulnerability for psychosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Numerical simulations of non-spherical bubble collapse.

    Science.gov (United States)

    Johnsen, Eric; Colonius, Tim

    2009-06-01

    A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined.

  13. Rg Wave Scattering from Collapse Craters in Yucca Flat, NV

    Science.gov (United States)

    Bonner, J. L.; Pitarka, A.

    2016-12-01

    Short-period, fundamental mode Rayleigh waves (Rg) have been used as indicators of shallow source depth and are often preferred waveform features for estimating yield and moment tensor for underground explosions recorded at local distances. However, in regions with significant topography and/or complex tectonic structure, Rg can be rapidly attenuated or scattered such that the phase may not be observed within a few kilometers of the source, thus limiting its seismological applications. A unique dataset was collected in Yucca Flat, Nevada that allows additional insight into the effect of surface topography on Rg. The source was a large weight drop (the Seismic Hammer™), which is an efficient surface wave generator. Stations were placed at similar distance ranges ( 0.5 km) in an azimuthal array centered on the hammer source. The source-to-station paths included deep alluvium with and without topography, the topography being the result of collapse craters associated with historic nuclear tests in Yucca Flat. The craters dimensions were as much 1/3 of the entire propagation paths, which were as deep as 30 m. For flat paths, we often observe large amplitude Rg waves in the 3-15 Hz frequency band that are slightly dispersed. Contrarily, paths that cross collapse craters exhibit reduced Rg amplitudes or, in one case, essentially no observed fundamental mode surface waves. We have used SW4, an elastic wave propagation code, and a 3D velocity model for Yucca Flat, with and without topography, to simulate wave propagation. The synthetic and recorded ground motion was analyzed to better understand the effects of topographic scattering. We anticipate that the results of these simulations will help improve the configuration of the seismic stations network designed for Phase II of the Source Physics Experiment.

  14. Can a collapse of global civilization be avoided?

    Science.gov (United States)

    Ehrlich, Paul R; Ehrlich, Anne H

    2013-03-07

    Environmental problems have contributed to numerous collapses of civilizations in the past. Now, for the first time, a global collapse appears likely. Overpopulation, overconsumption by the rich and poor choices of technologies are major drivers; dramatic cultural change provides the main hope of averting calamity.

  15. Collapse in a forced three-dimensional nonlinear Schrodinger equation

    DEFF Research Database (Denmark)

    Lushnikov, P.M.; Saffman, M.

    2000-01-01

    We derive sufficient conditions for the occurrence of collapse in a forced three-dimensional nonlinear Schrodinger equation without dissipation. Numerical studies continue the results to the case of finite dissipation.......We derive sufficient conditions for the occurrence of collapse in a forced three-dimensional nonlinear Schrodinger equation without dissipation. Numerical studies continue the results to the case of finite dissipation....

  16. Stability of naked singularity arising in gravitational collapse of Type ...

    Indian Academy of Sciences (India)

    to choose the velocity function and rest of the initial data so that the end state of collapse is either a black hole (BH) or a naked singularity (NS). This result is significant for two reasons: (1) It produces a substantially 'big' initial data set which under gravitational collapse results into a naked singularity. (2) Type I matter fields.

  17. Predicting epiglottic collapse in patients with obstructive sleep apnoea.

    Science.gov (United States)

    Azarbarzin, Ali; Marques, Melania; Sands, Scott A; Op de Beeck, Sara; Genta, Pedro R; Taranto-Montemurro, Luigi; de Melo, Camila M; Messineo, Ludovico; Vanderveken, Olivier M; White, David P; Wellman, Andrew

    2017-09-01

    Obstructive sleep apnoea (OSA) is characterised by pharyngeal obstruction occurring at different sites. Endoscopic studies reveal that epiglottic collapse renders patients at higher risk of failed oral appliance therapy or accentuated collapse on continuous positive airway pressure. Diagnosing epiglottic collapse currently requires invasive studies (imaging and endoscopy). As an alternative, we propose that epiglottic collapse can be detected from the distinct airflow patterns it produces during sleep.23 OSA patients underwent natural sleep endoscopy. 1232 breaths were scored as epiglottic/nonepiglottic collapse. Several flow characteristics were determined from the flow signal (recorded simultaneously with endoscopy) and used to build a predictive model to distinguish epiglottic from nonepiglottic collapse. Additionally, 10 OSA patients were studied to validate the pneumotachograph flow features using nasal pressure signals.Epiglottic collapse was characterised by a rapid fall(s) in the inspiratory flow, more variable inspiratory and expiratory flow and reduced tidal volume. The cross-validated accuracy was 84%. Predictive features obtained from pneumotachograph flow and nasal pressure were strongly correlated.This study demonstrates that epiglottic collapse can be identified from the airflow signal measured during a sleep study. This method may enable clinicians to use clinically collected data to characterise underlying physiology and improve treatment decisions. Copyright ©ERS 2017.

  18. Collapse arresting in an inhomogeneous quintic nonlinear Schrodinger model

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Schjødt-Eriksen, Jens; Christiansen, Peter Leth

    1999-01-01

    Collapse of (1 + 1)-dimensional beams in the inhomogeneous one-dimensional quintic nonlinear Schrodinger equation is analyzed both numerically and analytically. It is shown that in the vicinity of a narrow attractive inhomogeneity, the collapse of beams in which the homogeneous medium would blow up...

  19. The Role of Confinement in Bubble Collapse in a Channel

    Science.gov (United States)

    Rodriguez, Mauro; Alahyari Beig, Shahaboddin; Johnsen, Eric; Barbier, Charlotte

    2017-11-01

    In a variety of applications, cavitation bubbles collapse near solid objects give rise to damage in certain extreme cases. Numerous detailed computational studies have been conducted of a single bubble collapsing near a rigid wall. However, there are known situations where the bubbles collapse in a confined configuration, such as in biomedical applications and in the spallation neutron source. However, the effect of confinement (e.g., in the case of bubble collapse in a narrow channel) is poorly understood. In the present work, we quantify the effect of confinement on the bubble dynamics, pressures and temperatures produced from a single bubble collapsing in a channel. An in-house, solution-adaptive, high-order accurate shock- and interface-capturing method is used to solve the 3D compressible Navier-Stokes equations for gas/liquid flows. We demonstrate the conditions under which the channel walls strengthen/weaken the violence of the collapse and result in amplifying/reducing the wall pressures and temperatures. We further determine the smallest channel width, relative to the initial bubble radius, for which the presence of a second wall affects the collapse. Additional simulations of multiple bubbles collapsing in a channel are underway and will be discussed. This research was supported in part by ONR Grant N00014-12-1-0751 and NSF Grant CBET 1253157.

  20. Collapse of a Public-Private Partnership in

    African Journals Online (AJOL)

    This paper examines the collapse of a public-private partnership (PPP) in the district of U itenhage in 1999. Talks to revive the partnership are high on the agenda. It is therefore essential to examine the reasons for the collapse to avoid the pitfalls of the past and to ensure that a more sustainable and competent partnership ...

  1. Collapse arresters for deep water pipelines: identification of crossover mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Toscano, Rita G.; Mantovano, Luciano; Assanelli, Andrea; Amenta, Pablo; Johnson, Daniel; Charreau, Roberto; Dvorkin, Eduardo [Tenaris Center for industrial Research (CINI), Siderca, Campana (Argentina)

    2005-07-01

    Deep water pipelines, normally subjected to external pressure and bending, fail due to structural collapse when the external loading exceeds the pipes collapse limit surface. For steel pipes, the influence on this limit surface of manufacturing imperfections has been thoroughly studied by CINI using finite element models that have been validated via laboratory full-scale tests. After a steel pipeline collapses, the collapse is restrained to the collapse initiation section or it propagates along the pipeline, being this second alternative the most detrimental one for the pipeline integrity. Therefore, it is necessary to build in the pipeline periodic reinforcements, to act as arresters for the collapse propagation. Using finite element models, we study the crossover of collapse arresters by the propagating collapse. The occurrence of different crossover mechanisms is determined by the geometry of the pipes and of the arresters. Laboratory tests were carried out at CINI in order to obtain experimental results that could be used to validate the numerical models. In this paper, we compare the numerical and experimental results for external pressure lo (author)

  2. Fire-induced collapse mechanisms of steel buildings

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Aiuti, Riccardo; Bontempi, Franco

    2013-01-01

    significant in case the fire has spread through several floors, occurrence which is not contemplated by current fire design requirements, but that has been observed in most high-rise building fires. The results of the studies show that unfavourable collapse of single-story buildings and progressive collapse...

  3. Maternal Postpartum Role Collapse as a Theory of Postpartum Depression

    Science.gov (United States)

    Amankwaa, Linda Clark

    2005-01-01

    The purpose of this paper is to discuss the development of a theory of maternal postpartum role collapse. The influences of traditional role theory and symbolic interactionism are presented. The development of the maternal postpartum role collapse theory emerged from the study of postpartum depression among African-American women (Amankwaa, 2000).…

  4. Susceptibilité magnétique et indices polliniques, marqueurs de l'impact anthropique et de la dynamique fluviale dans la basse vallée du Doubs (Jura, France) entre le Ier et le VIIIe siècles après J.-C.Mineral magnetic susceptibility and palynological evidences of human impact and fluvial process in the lower Doubs valley (Jura, France) between 1st 8th century AD.

    Science.gov (United States)

    Vannière, Boris; Bossuet, Gilles; Gauthier, Emilie

    2000-08-01

    Surface scanning magnetic susceptibility, microscopic charcoal counting and pollen analysis have been carried out on two cores from the lower Doubs valley. The interpretation of anthropogenic pollen indicators is discussed in relation to the lithological variations of sedimentary accumulation. The environmental changes which occurred during the 1 st and the 6 th century AD reflect the impact of human activities on the landscape in the immediate surroundings of the site. Magnetic susceptibility and pollen analysis indicate soil erosion as a consequence of agricultural activity. A renewal of hydric activity of the river recorded in the sedimentary sequences attests of a larger environmental evolution during the 3 rd century AD.

  5. Deepwater demersal fish community collapse in Lake Huron

    Science.gov (United States)

    Riley, S.C.; Roseman, E.F.; Nichols, S.J.; O'Brien, T. P.; Kiley, C.S.; Schaeffer, J.S.

    2008-01-01

    Long-term fish community surveys were carried out in the Michigan waters of Lake Huron using bottom trawls from 1976 to 2006. Trends in abundance indices for common species (those caught in 10% or more of trawl tows) were estimated for two periods: early (1976-1991) and late (1994-2006). All common species significantly decreased in abundance during the late period with the exception of the johnny darter Etheostoma nigrum and spottail shiner Notropis hudsonius, which showed no significant trends, and the round goby Neogobius melanostomus, which increased in abundance. Percentage decreases in abundance indices between 1994-1995 and 2005-2006 ranged from 66.4% to 99.9%, and seven species decreased in abundance by more than 90%. The mean biomass of all common species in 2006 was the lowest observed in the time series and was less than 5% of that observed in the mid-1990s. The mean number of common species captured per trawl has also decreased since the mid-1990s. Several factors, including recent invasion of the lake by multiple exotic species, may have contributed to these declines, but insufficient published data are currently available to determine which factors are most important. Our observations suggest that significant changes have occurred in the ecology of Lake Huron since the mid-1990s. The extent of these changes indicates that the deepwater demersal fish community in Lake Huron is undergoing collapse.

  6. Drought, agricultural adaptation, and sociopolitical collapse in the Maya Lowlands.

    Science.gov (United States)

    Douglas, Peter M J; Pagani, Mark; Canuto, Marcello A; Brenner, Mark; Hodell, David A; Eglinton, Timothy I; Curtis, Jason H

    2015-05-05

    Paleoclimate records indicate a series of severe droughts was associated with societal collapse of the Classic Maya during the Terminal Classic period (∼800-950 C.E.). Evidence for drought largely derives from the drier, less populated northern Maya Lowlands but does not explain more pronounced and earlier societal disruption in the relatively humid southern Maya Lowlands. Here we apply hydrogen and carbon isotope compositions of plant wax lipids in two lake sediment cores to assess changes in water availability and land use in both the northern and southern Maya lowlands. We show that relatively more intense drying occurred in the southern lowlands than in the northern lowlands during the Terminal Classic period, consistent with earlier and more persistent societal decline in the south. Our results also indicate a period of substantial drying in the southern Maya Lowlands from ∼200 C.E. to 500 C.E., during the Terminal Preclassic and Early Classic periods. Plant wax carbon isotope records indicate a decline in C4 plants in both lake catchments during the Early Classic period, interpreted to reflect a shift from extensive agriculture to intensive, water-conservative maize cultivation that was motivated by a drying climate. Our results imply that agricultural adaptations developed in response to earlier droughts were initially successful, but failed under the more severe droughts of the Terminal Classic period.

  7. Film collapse behavior on high temperature particle surface

    Energy Technology Data Exchange (ETDEWEB)

    Tochio, Daisuke; Abe, Yutaka [Department of Mechanical Systems Engineering, Yamagata University, Yonezawa, Yamagata (Japan)

    1999-07-01

    It is pointed out that large-scale vapor explosion may occurred during a severe accident of a nuclear power plant. It is important to predict the possibility of the vapor explosion for the accident management of the nuclear power plant during a severe accident. The thermal detonation model is proposed to predict the vapor explosion. In the thermal detonation model, vapor explosion is started by a trigger. The trigger is vapor film collapse around high temperature material droplets coarsely pre-mixed in low temperature liquid. In the premixing stage, high temperature material droplets are insulated from low temperature liquid by the vapor film. Once the vapor film is collapsed, very quick and large heat transfer starts followed by the atomization. In order to clarify the trigger condition of the vapor explosion, it is necessary to identify the mechanism of the film collapse on the high temperature droplet surface in low temperature particle surface. Since the steam film on a high temperature droplet is unstable in high subcooling condition of low temperature liquid, the possibility of the self-collapse of the steam film is high. On the other hand, the possibility of the film collapse is not high in low subcooling or saturated condition since the steam film is tough. There are many experimental studies on the vapor film collapse behavior on the high temperature material surface. Most of those studies, vapor film collapse follows by the atomization , since melted droplets are used in those experiments. And the experiments used solid material is limited for the cylindrical or flat plate geometry. At present, there is no experimental database on the microscopic mechanism of steam film collapse behavior in spherical geometry for wide range of subcooling conditions. In the present study, steam film collapse behavior on a stainless steel particle surface is experimentally investigated. The stainless steel particle heated up by a burner is immersed into water in a stainless

  8. Hypernatremia and intravenous fluid resuscitation in collapsed ultramarathon runners.

    Science.gov (United States)

    Hew-Butler, Tamara; Boulter, Jeremy; Mbchb, John Godlonton; Phd, Ross Tucker; Mbchb, Timothy Noakes

    2008-05-01

    To determine if a return to normonatremia is required for symptomatology to resolve in collapsed hypernatremic runners and if intravenous (IV) administration of an isotonic solution would adversely affect serum sodium concentration ([Na+]) in collapsed normonatremic runners. Observational study. 2006 Comrades Marathon. 103 collapsed runners. Final serum [Na] upon discharge. 58% of all collapsed runners were hypernatremic. Hypernatremic runners reported significantly more vomiting than normonatremic runners (79 versus 34%; P 145 mmol/L). A return to normonatremia was not required for hypernatremic runners to "recover" and be discharged from the medical tent. Vomiting either aggravated and/or facilitated the development of hypernatremia. IV administration of 1 L of either (1) a hypotonic solution to hypernatremic runners or (2) an isotonic solution to both normonatremic and hypernatremic runners did not produce any adverse biochemical or cardiovascular changes and can therefore be considered a safe and effective treatment for collapsed runners if used in this context.

  9. EJSCREEN Demographic Indicators 2016 Public

    Data.gov (United States)

    U.S. Environmental Protection Agency — EJSCREEN uses demographic factors as very general indicators of a community's potential susceptibility to the types of environmental factors included in this...

  10. EJSCREEN Demographic Indicators 2015 Public

    Data.gov (United States)

    U.S. Environmental Protection Agency — EJSCREEN uses demographic factors as very general indicators of a community's potential susceptibility to the types of environmental factors included in this...

  11. Seepage Model for PA Including Dift Collapse

    Energy Technology Data Exchange (ETDEWEB)

    G. Li; C. Tsang

    2000-12-20

    The purpose of this Analysis/Model Report (AMR) is to document the predictions and analysis performed using the Seepage Model for Performance Assessment (PA) and the Disturbed Drift Seepage Submodel for both the Topopah Spring middle nonlithophysal and lower lithophysal lithostratigraphic units at Yucca Mountain. These results will be used by PA to develop the probability distribution of water seepage into waste-emplacement drifts at Yucca Mountain, Nevada, as part of the evaluation of the long term performance of the potential repository. This AMR is in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (CRWMS M&O 2000 [153447]). This purpose is accomplished by performing numerical simulations with stochastic representations of hydrological properties, using the Seepage Model for PA, and evaluating the effects of an alternative drift geometry representing a partially collapsed drift using the Disturbed Drift Seepage Submodel. Seepage of water into waste-emplacement drifts is considered one of the principal factors having the greatest impact of long-term safety of the repository system (CRWMS M&O 2000 [153225], Table 4-1). This AMR supports the analysis and simulation that are used by PA to develop the probability distribution of water seepage into drift, and is therefore a model of primary (Level 1) importance (AP-3.15Q, ''Managing Technical Product Inputs''). The intended purpose of the Seepage Model for PA is to support: (1) PA; (2) Abstraction of Drift-Scale Seepage; and (3) Unsaturated Zone (UZ) Flow and Transport Process Model Report (PMR). Seepage into drifts is evaluated by applying numerical models with stochastic representations of hydrological properties and performing flow simulations with multiple realizations of the permeability field around the drift. The Seepage Model for PA uses the distribution of permeabilities derived from air injection testing in

  12. Numerical modelling of collapsing volcanic edifices

    Science.gov (United States)

    Costa, Ana; Marques, Fernando; Kaus, Boris

    2017-04-01

    The flanks of Oceanic Volcanic Edifice's (OVEs) can occasionally become unstable. If that occurs, they can deform in two different modes: either slowly along localization failure zones (slumps) or catastrophically as debris avalanches. Yet the physics of this process is incompletely understood, and the role of factors such as the OVE's strength (viscosity, cohesion, friction angle), dimensions, geometry, and existence of weak layers remain to be addressed. Here we perform numerical simulations to study the interplay between viscous and plastic deformation on the gravitational collapse of an OVE (diffuse deformation vs. localization of failure along discrete structures). We focus on the contribution of the edifice's strength parameters for the mode of deformation, as well as on the type of basement. Tests were performed for a large OVE (7.5 km high, 200 km long) and either purely viscous (overall volcano edifice viscosities between 1019-1023 Pa.s), or viscoplastic rheology (within a range of cohesion and friction angle values). Results show that (a) for a strong basement (no slip basal boundary condition), the deformation pattern suggests wide/diffuse "listric" deformation within the volcanic edifice, without the development of discrete plastic failure zones; (b) for a weak basement (free slip basal boundary condition), rapid collapse of the edifice through the propagation of plastic failure structures within the edifice occurs. Tests for a smaller OVE (4.5 km by 30 km) show that failure localization along large-scale listric structures occurs more readily for different combinations of cohesion and friction angles. In these tests, high cohesion values combined with small friction angles lead to focusing of deformation along a narrower band. Tests with a weak layer underlying part of the volcanic edifice base show deformation focused along discrete structures mainly dipping towards the distal sector of the volcano. These tests for a small OVE constitute a promising

  13. Volcanic rock properties control sector collapse events

    Science.gov (United States)

    Hughes, Amy; Kendrick, Jackie; Lavallée, Yan; Hornby, Adrian; Di Toro, Giulio

    2017-04-01

    Volcanoes constructed by superimposed layers of varying volcanic materials are inherently unstable structures. The heterogeneity of weak and strong layers consisting of ash, tephra and lavas, each with varying coherencies, porosities, crystallinities, glass content and ultimately, strength, can promote volcanic flank and sector collapses. These volcanoes often exist in areas with complex regional tectonics adding to instability caused by heterogeneity, flank overburden, magma movement and emplacement in addition to hydrothermal alteration and anomalous geothermal gradients. Recent studies conducted on the faulting properties of volcanic rocks at variable slip rates show the rate-weakening dependence of the friction coefficients (up to 90% reduction)[1], caused by a wide range of factors such as the generation of gouge and frictional melt lubrication [2]. Experimental data from experiments conducted on volcanic products suggests that frictional melt occurs at slip rates similar to those of plug flow in volcanic conduits [1] and the bases of mass material movements such as debris avalanches from volcanic flanks [3]. In volcanic rock, the generation of frictional heat may prompt the remobilisation of interstitial glass below melting temperatures due to passing of the glass transition temperature at ˜650-750 ˚C [4]. In addition, the crushing of pores in high porosity samples can lead to increased comminution and strain localisation along slip surfaces. Here we present the results of friction tests on both high density, glass rich samples from Santaguito (Guatemala) and synthetic glass samples with varying porosities (0-25%) to better understand frictional properties underlying volcanic collapse events. 1. Kendrick, J.E., et al., Extreme frictional processes in the volcanic conduit of Mount St. Helens (USA) during the 2004-2008 eruption. J. Structural Geology, 2012. 2. Di Toro, G., et al., Fault lubrication during earthquakes. Nature, 2011. 471(7339): p. 494-498. 3

  14. Nucleosynthesis in Core-Collapse Supernovae

    Science.gov (United States)

    Stevenson, Taylor Shannon; Viktoria Ohstrom, Eva; Harris, James Austin; Hix, William R.

    2018-01-01

    The nucleosynthesis which occurs in core-collapse supernovae (CCSN) is one of the most important sources of elements in the universe. Elements from Oxygen through Iron come predominantly from supernovae, and contributions of heavier elements are also possible through processes like the weak r-process, the gamma process and the light element primary process. The composition of the ejecta depends on the mechanism of the explosion, thus simulations of high physical fidelity are needed to explore what elements and isotopes CCSN can contribute to Galactic Chemical Evolution. We will analyze the nucleosynthesis results from self-consistent CCSN simulations performed with CHIMERA, a multi-dimensional neutrino radiation-hydrodynamics code. Much of our understanding of CCSN nucleosynthesis comes from parameterized models, but unlike CHIMERA these fail to address essential physics, including turbulent flow/instability and neutrino-matter interaction. We will present nucleosynthesis predictions for the explosion of a 9.6 solar mass first generation star, relying both on results of the 160 species nuclear reaction network used in CHIMERA within this model and on post-processing with a more extensive network. The lowest mass iron core-collapse supernovae, like this model, are distinct from their more massive brethren, with their explosion mechanism and nucleosynthesis being more like electron capture supernovae resulting from Oxygen-Neon white dwarves. We will highlight the differences between the nucleosynthesis in this model and more massive supernovae. The inline 160 species network is a feature unique to CHIMERA, making this the most sophisticated model to date for a star of this type. We will discuss the need and mechanism to extrapolate the post-processing to times post-simulation and analyze the uncertainties this introduces for supernova nucleosynthesis. We will also compare the results from the inline 160 species network to the post-processing results to study further

  15. Susceptibility to malignant hyperthermia

    NARCIS (Netherlands)

    Snoeck, Marcus Matheus Johannes

    2004-01-01

    In this thesis the author studied the diagnostic procedures for susceptibility to malignant hyperthermia (MH), with special emphasis upon refining the biological diagnostic test and improving protocols and guidelines for investigation of MH susceptibility. MH is a pharmacogenetic disease of skeletal

  16. Enzymatic collapse of artificial polymer composite material containing double-stranded DNA.

    Science.gov (United States)

    Yamada, Masanori; Amoo, Mariko

    2008-06-01

    Large amounts of DNA-enriched biomaterials, such as salmon milts and shellfish gonads, are discarded as industrial waste around the world. Therefore, the utilizations of DNA with the specific function are important for the biomaterial science and the curce technology. We could convert the discarded DNA to an enzymatic collapsible material by the addition of DNA to the artificial polymer material, such as nylon. Although these DNA-artificial polymer composite materials were stable in water, these materials indicated the collapsibility at the DNA-hydrolyzed enzyme, such as Micrococcal nuclease, condition. Additionally, these collapsibilities under enzyme condition were controlled by the number of imino groups in the components of the artificial polymer. Furthermore, these composite materials could create the fiber form with a highly ordered molecular orientation by the reaction at the liquid/liquid interface. The DNA-artificial polymer composite materials may have the potential utility as a novel bio-, medical-, and environmental materials with the enzymatic collapsibility and degradability.

  17. Quantum gravitational dust collapse does not result in a black hole

    Energy Technology Data Exchange (ETDEWEB)

    Vaz, Cenalo, E-mail: Cenalo.Vaz@uc.edu

    2015-02-15

    Quantum gravity suggests that the paradox recently put forward by Almheiri et al. (AMPS) can be resolved if matter does not undergo continuous collapse to a singularity but condenses on the apparent horizon. One can then expect a quasi-static object to form even after the gravitational field has overcome any degeneracy pressure of the matter fields. We consider dust collapse. If the collapse terminates on the apparent horizon, the Misner–Sharp mass function of the dust ball is predicted and we construct static solutions with no tangential pressure that would represent such a compact object. The collapse wave functions indicate that there will be processes by which energy extraction from the center occurs. These leave behind a negative point mass at the center which contributes to the total energy of the system but has no effect on the energy density of the dust ball. The solutions describe a compact object whose boundary lies outside its Schwarzschild radius and which is hardly distinguishable from a neutron star.

  18. Syntaxin 1B suppresses macropinocytosis and semaphorin 3A-induced growth cone collapse.

    Science.gov (United States)

    Kabayama, Hiroyuki; Takeuchi, Makoto; Taniguchi, Masahiko; Tokushige, Naoko; Kozaki, Shunji; Mizutani, Akihiro; Nakamura, Takeshi; Mikoshiba, Katsuhiko

    2011-05-18

    Growth cone collapse is a crucial process for repulsive axon guidance and is accompanied by a reduction in growth cone surface area. This process of reduction may be regulated by endocytosis; however, its molecular mechanism is unclear. Macropinocytosis is a clathrin-independent form of endocytosis in which large areas of plasma membrane can be engulfed. We have reported previously that macropinocytosis is induced in growth cones of chick dorsal root ganglion neurons by semaphorin 3A (Sema3A), a repulsive axon guidance cue, and that Sema3A-induced reduction in growth cone surface area and macropinocytic vacuole area were correlated, suggesting a positive role for macropinocytosis in Sema3A-induced growth cone collapse. In the present study, we found that syntaxin 1B (Syx1B), a membrane trafficking protein, is a negative regulator of macropinocytosis, and its expression is downregulated by Sema3A signaling. Macropinocytosis inhibitor ethylisopropylamiloride or Syx1B overexpression suppressed Sema3A-induced macropinocytosis and growth cone collapse. These results indicate that Syx1B couples macropinocytosis-mediated massive internalization of the plasma membrane to Sema3A-induced growth cone collapse.

  19. Shock wave emission upon spherical bubble collapse during cavitation-induced megasonic surface cleaning.

    Science.gov (United States)

    Minsier, V; Proost, J

    2008-04-01

    When a gas bubble in a liquid interacts with an acoustic wave near a solid surface, the bubble first expands and then collapses. In this paper, a mathematical framework combining the Gilmore model and the method of characteristics is presented to model the shock wave emitted at the end of the bubble collapse. It allows to describe the liquid velocity at the shock front as a function of the radial distance to the bubble center in the case of spherical bubble collapse. Numerical calculations of the liquid velocity at the shock front have shown that this velocity increases with the acoustic amplitude and goes through a maximum as a function of the initial bubble radius. Calculations for different gas state equations inside the bubble show that the Van der Waals law predicts a slightly higher liquid velocity at the shock front than when considering a perfect gas law. Finally, decreasing the value of the surface tension at the bubble/liquid interface results in an increase of the liquid velocity at the shock front. Our calculations indicate that the strength of the shock waves emitted upon spherical bubble collapse can cause delamination of typical device structures used in microelectronics.

  20. One-stage posterior instrumentation surgery for the treatment of osteoporotic vertebral collapse with neurological deficits

    Science.gov (United States)

    Ito, Manabu; Abumi, Kuniyoshi; Kotani, Yoshihisa; Takahata, Masahiko; Hojo, Yoshihiro; Minami, Akio

    2010-01-01

    The number of reports describing osteoporotic vertebral fracture has increased as the number of elderly people has grown. Anterior decompression and fusion alone for the treatment of vertebral collapse is not easy for patients with comorbid medical problems and severe bone fragility. The purpose of the present study was to evaluate the efficacy of one-stage posterior instrumentation surgery for the treatment of osteoporotic vertebral collapse with neurological deficits. A consecutive series of 21 patients who sustained osteoporotic vertebral collapse with neurological deficits were managed with posterior decompression and short-segmental pedicle screw instrumentation augmented with ultra-high molecular weight polyethylene (UHMWP) cables with or without vertebroplasty using calcium phosphate cement. The mean follow-up was 42 months. All patients showed neurologic recovery. Segmental kyphotic angle at the instrumented level was significantly improved from an average preoperative kyphosis of 22.8–14.7 at a final follow-up. Spinal canal occupation was significantly reduced from an average before surgery of 40.4–19.1% at the final follow-up. Two patients experienced loosening of pedicle screws and three patients developed subsequent vertebral compression fractures within adjacent segments. However, these patients were effectively treated in a conservative fashion without any additional surgery. Our results indicated that one-stage posterior instrumentation surgery augmented with UHMWP cables could provide significant neurological improvement in the treatment of osteoporotic vertebral collapse. PMID:20157741

  1. Quantum gravitational dust collapse does not result in a black hole

    Directory of Open Access Journals (Sweden)

    Cenalo Vaz

    2015-02-01

    Full Text Available Quantum gravity suggests that the paradox recently put forward by Almheiri et al. (AMPS can be resolved if matter does not undergo continuous collapse to a singularity but condenses on the apparent horizon. One can then expect a quasi-static object to form even after the gravitational field has overcome any degeneracy pressure of the matter fields. We consider dust collapse. If the collapse terminates on the apparent horizon, the Misner–Sharp mass function of the dust ball is predicted and we construct static solutions with no tangential pressure that would represent such a compact object. The collapse wave functions indicate that there will be processes by which energy extraction from the center occurs. These leave behind a negative point mass at the center which contributes to the total energy of the system but has no effect on the energy density of the dust ball. The solutions describe a compact object whose boundary lies outside its Schwarzschild radius and which is hardly distinguishable from a neutron star.

  2. Sub-surface structures and collapse mechanisms of summit pit craters

    Science.gov (United States)

    Roche, O.; van Wyk de Vries, B.; Druitt, T. H.

    2001-01-01

    Summit pit craters are found in many types of volcanoes and are generally thought to be the product of collapse into an underpressured reservoir caused by magma withdrawal. We investigate the mechanisms and structures associated with summit pit crater formation by scaled analogue experiments and make comparisons with natural examples. Models use a sand plaster mixture as analogue rock over a cylinder of silicone simulating an underpressured magma reservoir. Experiments are carried out using different roof aspect ratios (roof thickness/roof width) of 0.2-2. They reveal two basic collapse mechanisms, dependant on the roof aspect ratio. One occurs at low aspect ratios (≤1), as illustrated by aspect ratios of 0.2 and 1. Outward dipping reverse faults initiated at the silicone margins propagates through the entire roof thickness and cause subsidence of a coherent block. Collapse along the reverse faults is accommodated by marginal flexure of the block and tension fractures at the surface (aspect ratio of 0.2) or by the creation of inward dipping normal faults delimiting a terrace (aspect ratio of 1). At an aspect ratio of 1, overhanging pit walls are the surface expressions of the reverse faults. Experiments at high aspect ratio (>1.2) reveal a second mechanism. In this case, collapse occurs by stopping, which propagates upwards by a complex pattern of both reverse faults and tension fractures. The initial underground collapse is restricted to a zone above the reservoir and creates a cavity with a stable roof above it. An intermediate mechanism occurs at aspect ratios of 1.1-1.2. In this case, stopping leads to the formation of a cavity with a thin and unstable roof, which collapses suddenly. The newly formed depression then exhibits overhanging walls. Surface morphology and structure of natural examples, such as the summit pit craters at Masaya Volcano, Nicaragua, have many of the features created in the models, indicating that the internal structural geometry of

  3. Colony Collapse Disorder: A Descriptive Study

    Science.gov (United States)

    vanEngelsdorp, Dennis; Evans, Jay D.; Saegerman, Claude; Mullin, Chris; Haubruge, Eric; Nguyen, Bach Kim; Frazier, Maryann; Frazier, Jim; Cox-Foster, Diana; Chen, Yanping; Underwood, Robyn; Tarpy, David R.; Pettis, Jeffery S.

    2009-01-01

    Background Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L.) colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD) because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. Methods and Principal Findings Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels), no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor) were higher in control colonies than CCD-affected colonies. Conclusions/Significance This is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted. PMID:19649264

  4. Tulsa Oklahoma Oktoberfest Tent Collapse Report

    Directory of Open Access Journals (Sweden)

    Kelly E. Deal

    2012-01-01

    Full Text Available Background. On October 17, 2007, a severe weather event collapsed two large tents and several smaller tents causing 23 injuries requiring evacuation to emergency departments in Tulsa, OK. Methods. This paper is a retrospective analysis of the regional health system’s response to this event. Data from the Tulsa Fire Department, The Emergency Medical Services Authority (EMSA, receiving hospitals and coordinating services were reviewed and analyzed. EMS patient care reports were reviewed and analyzed using triage designators assigned in the field, injury severity scores, and critical mortality. Results. EMT's and paramedics from Tulsa Fire Department and EMSA provided care at the scene under unified incident command. Of the 23 patients transported by EMS, four were hospitalized, one with critical spinal injury and one with critical head injury. One patient is still in ongoing rehabilitation. Discussion. Analysis of the 2007 Tulsa Oktoberfest mass casualty incident revealed rapid police/fire/EMS response despite challenges of operations at dark under severe weather conditions and the need to treat a significant number of injured victims. There were no fatalities. Of the patients transported by EMS, a minority sustained critical injuries, with most sustaining injuries amenable to discharge after emergency department care.

  5. Colony collapse disorder: a descriptive study.

    Directory of Open Access Journals (Sweden)

    Dennis Vanengelsdorp

    Full Text Available BACKGROUND: Over the last two winters, there have been large-scale, unexplained losses of managed honey bee (Apis mellifera L. colonies in the United States. In the absence of a known cause, this syndrome was named Colony Collapse Disorder (CCD because the main trait was a rapid loss of adult worker bees. We initiated a descriptive epizootiological study in order to better characterize CCD and compare risk factor exposure between populations afflicted by and not afflicted by CCD. METHODS AND PRINCIPAL FINDINGS: Of 61 quantified variables (including adult bee physiology, pathogen loads, and pesticide levels, no single measure emerged as a most-likely cause of CCD. Bees in CCD colonies had higher pathogen loads and were co-infected with a greater number of pathogens than control populations, suggesting either an increased exposure to pathogens or a reduced resistance of bees toward pathogens. Levels of the synthetic acaricide coumaphos (used by beekeepers to control the parasitic mite Varroa destructor were higher in control colonies than CCD-affected colonies. CONCLUSIONS/SIGNIFICANCE: This is the first comprehensive survey of CCD-affected bee populations that suggests CCD involves an interaction between pathogens and other stress factors. We present evidence that this condition is contagious or the result of exposure to a common risk factor. Potentially important areas for future hypothesis-driven research, including the possible legacy effect of mite parasitism and the role of honey bee resistance to pesticides, are highlighted.

  6. Flux-driven simulations of turbulence collapse

    Energy Technology Data Exchange (ETDEWEB)

    Park, G. Y.; Kim, S. S.; Jhang, Hogun; Rhee, T. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Diamond, P. H. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); CASS and Department of Physics, University of California, San Diego, La Jolla, California 92093-0429 (United States); Xu, X. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2015-03-15

    Using three-dimensional nonlinear simulations of tokamak turbulence, we show that an edge transport barrier (ETB) forms naturally once input power exceeds a threshold value. Profiles, turbulence-driven flows, and neoclassical coefficients are evolved self-consistently. A slow power ramp-up simulation shows that ETB transition is triggered by the turbulence-driven flows via an intermediate phase which involves coherent oscillation of turbulence intensity and E×B flow shear. A novel observation of the evolution is that the turbulence collapses and the ETB transition begins when R{sub T} > 1 at t = t{sub R} (R{sub T}: normalized Reynolds power), while the conventional transition criterion (ω{sub E×B}>γ{sub lin} where ω{sub E×B} denotes mean flow shear) is satisfied only after t = t{sub C} ( >t{sub R}), when the mean flow shear grows due to positive feedback.

  7. Study of film boiling collapse behavior during vapor explosion

    Energy Technology Data Exchange (ETDEWEB)

    Yagi, Masahiro; Yamano, Norihiro; Sugimoto, Jun [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Abe, Yutaka; Adachi, Hiromichi; Kobayashi, Tomoyoshi

    1996-06-01

    Possible large scale vapor explosions are safety concern in nuclear power plants during severe accident. In order to identify the occurrence of the vapor explosion and to estimate the magnitude of the induced pressure pulse, it is necessary to investigate the triggering condition for the vapor explosion. As a first step of this study, scooping analysis was conducted with a simulation code based on thermal detonation model. It was found that the pressure at the collapse of film boiling much affects the trigger condition of vapor explosion. Based on this analytical results, basic experiments were conducted to clarify the collapse conditions of film boiling on a high temperature solid ball surface. Film boiling condition was established by flooding water onto a high temperature stainless steel ball heated by a high frequency induction heater. After the film boiling was established, the pressure pulse generated by a shock tube was applied to collapse the steam film on the ball surface. As the experimental boundary conditions, materials and size of the balls, magnitude of pressure pulse and initial temperature of the carbon and stainless steel balls were varied. The transients of pressure and surface temperature were measured. It was found that the surface temperature on the balls sharply decreased when the pressure wave passed through the film on balls. Based on the surface temperature behavior, the film boiling collapse pattern was found to be categorized into several types. Especially, the pattern for stainless steel ball was categorized into three types; no collapse, collapse and reestablishment after collapse. It was thus clarified that the film boiling collapse behavior was identified by initial conditions and that the pressure required to collapse film boiling strongly depended on the initial surface temperature. The present results will provide a useful information for the analysis of vapor explosions based on the thermal detonation model. (J.P.N.)

  8. APPLICATION OF AEM IN PROGRESSIVE COLLAPSE DYNAMICS ANALYSIS OF R.C. STRUCTURES

    Directory of Open Access Journals (Sweden)

    Osama El-Mahdy

    2018-01-01

    Full Text Available The Finite Element Method (FEM and the other numerical strategies are viably actualized in linear and non-linear analysis of structures. Recently, a new displacement based on Applied Element Method (AEM has been developed. It is applicable for static and dynamic for both linear and non-linear analysis of framed and continuum structures. In AEM, the structural member is partitioned into virtual elements connected through normal and shear springs representing stresses and strains of certain portion of structure. FEM assumes the material as continuous and can indicate highly stressed region of structure, however it is difficult to model separation of element unless crack location is known. The main advantage of AEM is that it can track the structural collapse behavior going through all phases of the application of loads. In the current research, the application of AEM is illustrated through a non-linear dynamic analysis. Progressive collapse simulation is conducted using Extreme Loading for Structures software (ELS, which follows the AEM. The experimental and analytical works carried by Park et al. [17 and 28] for 1/5 scaled 3 and 5 stories reinforced concrete structures are used for verification. Good matching between the experimental and numerical results has been obtained using ELS. Therefore, it can be confirmed that ELS is capable in simulating the structures’ behavior up to collapse. Furthermore, a study has been made to investigate the effect of considering the floor slabs on progressive collapse. The results show that considering slab in progressive collapse analysis of multistory buildings is important as neglecting the slabs’ contribution leads to incorrect simulation and uneconomic design.

  9. The Baryonic Collapse Efficiency of Galaxy Groups in the RESOLVE and ECO Surveys

    Science.gov (United States)

    Eckert, Kathleen D.; Kannappan, Sheila J.; Lagos, Claudia del P.; Baker, Ashley D.; Berlind, Andreas A.; Stark, David V.; Moffett, Amanda J.; Nasipak, Zachary; Norris, Mark A.

    2017-11-01

    We examine the z = 0 group-integrated stellar and cold baryonic (stars + cold atomic gas) mass functions (group SMF and CBMF) and the baryonic collapse efficiency (group cold baryonic to dark matter halo mass ratio) using the RESOLVE and ECO survey galaxy group catalogs and a galform semi-analytic model (SAM) mock catalog. The group SMF and CBMF fall off more steeply at high masses and rise with a shallower low-mass slope than the theoretical halo mass function (HMF). The transition occurs at the group-integrated cold baryonic mass {M}{bary}{cold} ∼ 1011 {M}ȯ . The SAM, however, has significantly fewer groups at the transition mass ∼1011 {M}ȯ and a steeper low-mass slope than the data, suggesting that feedback is too weak in low-mass halos and conversely too strong near the transition mass. Using literature prescriptions to include hot halo gas and potential unobservable galaxy gas produces a group BMF with a slope similar to the HMF even below the transition mass. Its normalization is lower by a factor of ∼2, in agreement with estimates of warm-hot gas making up the remaining difference. We compute baryonic collapse efficiency with the halo mass calculated two ways, via halo abundance matching (HAM) and via dynamics (extended all the way to three-galaxy groups using stacking). Using HAM, we find that baryonic collapse efficiencies reach a flat maximum for groups across the halo mass range of {M}{halo}∼ {10}11.4-12 {M}ȯ , which we label “nascent groups.” Using dynamics, however, we find greater scatter in baryonic collapse efficiencies, likely indicating variation in group hot-to-cold baryon ratios. Similarly, we see higher scatter in baryonic collapse efficiencies in the SAM when using its true groups and their group halo masses as opposed to friends-of-friends groups and HAM masses.

  10. Mass tree mortality leads to mangrove peat collapse at Bay Islands, Honduras after Hurricane Mitch

    Science.gov (United States)

    Cahoon, D.R.; Hensel, P.; Rybczyk, J.; McKee, K.L.; Proffitt, C.E.; Perez, B.C.

    2003-01-01

    We measured sediment elevation and accretion dynamics in mangrove forests on the islands of Guanaja and Roatan, Honduras, impacted by Hurricane Mitch in 1998 to determine if collapse of underlying peat was occurring as a result of mass tree mortality. Little is known about the balance between production and decomposition of soil organic matter in the maintenance of sediment elevation of mangrove forests with biogenic soils. Sediment elevation change measured with the rod surface elevation table from 18 months to 33 months after the storm differed significantly among low, medium and high wind impact sites. Mangrove forests suffering minimal to partial mortality gained elevation at a rate (5 mm yeara??1) greater than vertical accretion (2 mm yeara??1) measured from artificial soil marker horizons, suggesting that root production contributed to sediment elevation. Basin forests that suffered mass tree mortality experienced peat collapse of about 11 mm yeara??1 as a result of decomposition of dead root material and sediment compaction. Low soil shear strength and lack of root growth accompanied elevation decreases. Model simulations using the Relative Elevation Model indicate that peat collapse in the high impact basin mangrove forest would be 37 mm yeara??1 for the 2 years immediately after the storm, as root material decomposed. In the absence of renewed root growth, the model predicts that peat collapse will continue for at least 8 more years at a rate (7 mm yeara??1) similar to that measured (11 mm yeara??1). Mass tree mortality caused rapid elevation loss. Few trees survived and recovery of the high impact forest will thus depend primarily on seedling recruitment. Because seedling establishment is controlled in large part by sediment elevation in relation to tide height, continued peat collapse could further impair recovery rates.

  11. Coexistence of collapse and stable spatiotemporal solitons in multimode fibers

    Science.gov (United States)

    Shtyrina, Olga V.; Fedoruk, Mikhail P.; Kivshar, Yuri S.; Turitsyn, Sergei K.

    2018-01-01

    We analyze spatiotemporal solitons in multimode optical fibers and demonstrate the existence of stable solitons, in a sharp contrast to earlier predictions of collapse of multidimensional solitons in three-dimensional media. We discuss the coexistence of blow-up solutions and collapse stabilization by a low-dimensional external potential in graded-index media, and also predict the existence of stable higher-order nonlinear waves such as dipole-mode spatiotemporal solitons. To support the main conclusions of our numerical studies we employ a variational approach and derive analytically the stability criterion for input powers for the collapse stabilization.

  12. Nonspherically Symmetric Collapse in Asymptotically AdS Spacetimes

    Science.gov (United States)

    Bantilan, Hans; Figueras, Pau; Kunesch, Markus; Romatschke, Paul

    2017-11-01

    We numerically simulate gravitational collapse in asymptotically anti-de Sitter spacetimes away from spherical symmetry. Starting from initial data sourced by a massless real scalar field, we solve the Einstein equations with a negative cosmological constant in five spacetime dimensions and obtain a family of nonspherically symmetric solutions, including those that form two distinct black holes on the axis. We find that these configurations collapse faster than spherically symmetric ones of the same mass and radial compactness. Similarly, they require less mass to collapse within a fixed time.

  13. Absorbable Implant to Treat Nasal Valve Collapse.

    Science.gov (United States)

    San Nicoló, Marion; Stelter, Klaus; Sadick, Haneen; Bas, Murat; Berghaus, Alexander

    2017-04-01

    Objective To evaluate the safety and effectiveness of an absorbable implant for lateral cartilage support in subjects with nasal valve collapse (NVC) with 12 months follow-up. Methods Thirty subjects with Nasal Obstruction Symptom Evaluation (NOSE) score ≥ 55 and isolated NVC were treated; 14 cases were performed in an operating suite under general anesthesia and 16 cases were performed in a clinic-based setting under local anesthesia. The implant, a polylactic acid copolymer, was placed with a delivery tool within the nasal wall to provide lateral cartilage support. Subjects were followed up through 12 months postprocedure. Results Fifty-six implants were placed in 30 subjects. The mean preoperative NOSE score was 76.7 ± 14.8, with a range of 55 to 100. At 12 months, the mean score was 35.2 ± 29.2, reflecting an average within-patient reduction of -40.9 ± 31.2 points. The majority (76%) of the subjects were responders defined as having at least one NOSE class improvement or a NOSE score reduction of at least 20%. There were no adverse changes in cosmetic appearance at 12 months postprocedure. Three implants in three subjects required retrieval within 30 days postprocedure and resulted in no clinical sequelae. Conclusion This study demonstrates safety and effectiveness of an absorbable implant for lateral cartilage support in subjects with NVC at 12 months postprocedure. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  14. SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

    Energy Technology Data Exchange (ETDEWEB)

    C. Tsang

    2004-09-22

    The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, the van Genuchten 1/a parameter, and percolation flux) and drift degradation shape scenarios in support of the TSPA-LA during the period of compliance for postclosure performance [Technical Work Plan for: Performance Assessment Unsaturated Zone (BSC 2002 [DIRS 160819], Section I-4-2-1)]. The flow-focusing model in the Topopah Spring welded (TSw) unit is intended to provide an estimate of flow focusing factors (FFFs) that (1) bridge the gap between the mountain-scale and drift-scale models, and (2) account for variability in local percolation flux due to

  15. CATASTROPHIC FLANK COLLAPSE ON TA’U ISLAND AND SUBSEQUENT TSUNAMI: HAS THIS OCCURRED DURING THE LAST 170 YEARS?

    Directory of Open Access Journals (Sweden)

    Shaun Williams

    2012-01-01

    Full Text Available Ta’u, the easternmost inhabited island in the Samoan Islands archipelago, exhibits a series of down-faulted benches on its southern flank, believed to be the remnant of ~30 km3 catastrophic collapse. A historical map of Ta’u charted in 1839 during the United States Exploring Expedition, which did not show the benches, suggests that the event occurred less than 170 years ago. A collapse event of this magnitude would have generated a locally devastating tsunami, with possible impacts experienced at the regional level. However, no written or oral records of such an event exist. A number of key questions thus emerge, and formed the basis for this study. Did this event actually happen within the last 170 years, and if so, how and why could it have gone unnoticed? Or, is the event much older than the impression obtained from the literature? The catastrophic flank collapse was modeled using 100 m contour-resolution bathymetry data of the Ta’u region, coupled with rational assumptions made on the geometry of the failed mass. This enabled numerical landslide- tsunami simulation in the Cornell Multigrid Coupled Tsunami Model (COMCOT. The results indicate that if an event of this magnitude occurred in the last 170 years, it could not have gone unnoticed by local inhabitants. It thus seems likely that the initial survey conducted during the Exploring Expedition was inaccurate. Nevertheless, the well-preserved nature of the benches indicates collapse relatively recently and raises the possibility of future collapse.

  16. On the causes of collapse and sudden death by Avicenna.

    Science.gov (United States)

    Nathan, B; Wray, R

    1997-06-01

    Avicenna's views on the causes of collapse and sudden death are presented from a literal translation of the mediaeval Arabic text. Medical knowledge based on observation mixed with pure abstract reasoning forms the essence of Avicenna's medical writings.

  17. Algebraic properties and spectral collapse in nonlinear quantum Rabi models

    Science.gov (United States)

    Penna, V.; Raffa, F. A.; Franzosi, R.

    2018-01-01

    We investigate the origin of spectral collapse occurring in nonlinear Rabi Hamiltonians with an su(1,1) coupling scheme, showing how the collapse can be triggered by the competition between the Rabi parameter g and the field frequency W. The collapse already appears in the model Hamiltonian where the atomic-energy term is absent. After showing that su(1,1) is the dynamical algebra of the Hamiltonian, we demonstrate how the occurrence of spectral collapse can be directly related to the three types of equivalence classes characterizing the structure of this algebra. We highlight how the dramatic change of the spectrum significantly affects the structure of eigenstates represented in a suitable momentum–coordinate picture.

  18. Critical fitness collapse in three-dimensional spatial population genetics

    Science.gov (United States)

    Lavrentovich, Maxim O.

    2015-05-01

    If deleterious mutations near a fitness maximum in a spatially distributed population are sufficiently frequent or detrimental, the population can undergo a fitness collapse, similarly to the Muller's ratchet effect in well-mixed populations. Recent studies of 1D habitats (e.g. the frontier of a 2D range expansion) have shown that the onset of the fitness collapse is described by a directed percolation phase transition with its associated critical exponents. We consider population fitness collapse in 3D range expansions with both inflating and fixed-size frontiers (applicable to, e.g. expanding and treadmilling spherical tumors, respectively). We find that the onset of fitness collapse in these two cases obeys different scaling laws, and that competition between species at the frontier leads to a deviation from directed percolation scaling. As in 2D range expansions, inflating frontiers modify the critical behavior by causally disconnecting well-separated portions of the population.

  19. Gravitational collapses to bodies of a finite volume

    OpenAIRE

    Marsico, Tiziana; Loinger, Angelo

    2006-01-01

    We prove with an exact relativistic computation that the spherosymmetric gravitational collapses with a time-dependent pressure end in bodies with a small, but finite volume. Against a diffuse, wrong conviction.

  20. Modelling the self-organization and collapse of complex networks

    Indian Academy of Sciences (India)

    Modelling the self-organization and collapse of complex networks. Sanjay Jain Department of Physics and Astrophysics, University of Delhi Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore Santa Fe Institute, Santa Fe, New Mexico.

  1. The role of fluid viscosity in an immersed granular collapse

    Directory of Open Access Journals (Sweden)

    Yang Geng Chao

    2017-01-01

    Full Text Available Instabilities of immersed slopes and cliffs can lead to catastrophic events that involve a sudden release of huge soil mass. The scaled deposit height and runout distance are found to follow simple power laws when a granular column collapses on a horizontal plane. However, if the granular column is submerged in a fluid, the mobility of the granular collapse due to high inertia effects will be reduced by fluid-particle interactions. In this study, the effects of fluid viscosity on granular collapse is investigated qualitatively by adopting a numerical approach based on the coupled lattice Boltzmann method (LBM and discrete element method (DEM. It is found that the granular collapse can be dramatically slowed down due to the presence of viscous fluids. For the considered granular configuration, when the fluid viscosity increases. the runout distance decreases and the final deposition shows a larger deposit angle.

  2. Towards the Core-Collapse Supernova Explosion Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Cardall, Christian Y [ORNL; Endeve, Eirik [ORNL; Budiardja, R. D. [University of Tennessee, Knoxville (UTK); Marronetti, Pedro [Florida Atlantic University, Boca Raton; Mezzacappa, Anthony [ORNL

    2012-01-01

    Core-collapse supernovae are amazing displays of astrohysical fireworks - and the optical emission is only a tiny part of the story. These events involve virtually all branches of physics and spawn phenomena observale by every kind of astronomical observation. This richness of theory and observation presents a formidable challenge to their understanding via computer simulations, but we are entering a new era of realism and maturity in modeling the key processes by collapse and explosion.

  3. Singularity in Gravitational Collapse of Plane Symmetric Charged Vaidya Spacetime

    CERN Document Server

    Sharif, M

    2010-01-01

    We study the final outcome of gravitational collapse resulting from the plane symmetric charged Vaidya spacetime. Using the field equations, we show that the weak energy condition is always satisfied by collapsing fluid. It is found that the singularity formed is naked. The strength of singularity is also investigated by using Nolan's method. This turns out to be a strong curvature singularity in Tipler's sense and hence provides a counter example to the cosmic censorship hypothesis.

  4. Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

    OpenAIRE

    Ziaie, Amir Hadi; Moniz, Paulo Vargas; Ranjbar, Arash; Sepangi, Hamid Reza

    2013-01-01

    We consider the gravitational collapse of a spherically symmetric homogeneous matter distribution consisting of a Weyssenhoff fluid in the presence of a negative cosmological constant. Our aim is to investigate the effects of torsion and spin averaged terms on the final outcome of the collapse. For a specific interior spacetime setup, namely the homogeneous and isotropic FLRW metric, we obtain two classes of solutions to the field equations where depending on the relation between spin source ...

  5. Collapse of the soap-film bridge - Quasistatic description

    Science.gov (United States)

    Cryer, Steven A.; Steen, Paul H.

    1992-01-01

    Observations of the collapse of a soap-film bridge from a connected to a disconnected state are recorded. The equilibrium framework for this nonequilibrium event is classical. Experiments confirm predictions of stable and unstable equilibria. A quasistatic description is introduced for the dynamic states to extend the static theory. It is found to adequately describe the collapse trajectory while the bridge is still connected.

  6. Ongoing collapse of coral-reef shark populations.

    Science.gov (United States)

    Robbins, William D; Hisano, Mizue; Connolly, Sean R; Choat, J Howard

    2006-12-05

    Marine ecosystems are suffering severe depletion of apex predators worldwide; shark declines are principally due to conservative life-histories and fisheries overexploitation. On coral reefs, sharks are strongly interacting apex predators and play a key role in maintaining healthy reef ecosystems. Despite increasing fishing pressure, reef shark catches are rarely subject to specific limits, with management approaches typically depending upon no-take marine reserves to maintain populations. Here, we reveal that this approach is failing by documenting an ongoing collapse in two of the most abundant reef shark species on the Great Barrier Reef (Australia). We find an order of magnitude fewer sharks on fished reefs compared to no-entry management zones that encompass only 1% of reefs. No-take zones, which are more difficult to enforce than no-entry zones, offer almost no protection for shark populations. Population viability models of whitetip and gray reef sharks project ongoing steep declines in abundance of 7% and 17% per annum, respectively. These findings indicate that current management of no-take areas is inadequate for protecting reef sharks, even in one of the world's most-well-managed reef ecosystems. Further steps are urgently required for protecting this critical functional group from ecological extinction.

  7. Dating Antarctic ice sheet collapse: Proposing a molecular genetic approach

    Science.gov (United States)

    Strugnell, Jan M.; Pedro, Joel B.; Wilson, Nerida G.

    2018-01-01

    Sea levels at the end of this century are projected to be 0.26-0.98 m higher than today. The upper end of this range, and even higher estimates, cannot be ruled out because of major uncertainties in the dynamic response of polar ice sheets to a warming climate. Here, we propose an ecological genetics approach that can provide insight into the past stability and configuration of the West Antarctic Ice Sheet (WAIS). We propose independent testing of the hypothesis that a trans-Antarctic seaway occurred at the last interglacial. Examination of the genomic signatures of bottom-dwelling marine species using the latest methods can provide an independent window into the integrity of the WAIS more than 100,000 years ago. Periods of connectivity facilitated by trans-Antarctic seaways could be revealed by dating coalescent events recorded in DNA. These methods allow alternative scenarios to be tested against a fit to genomic data. Ideal candidate taxa for this work would need to possess a circumpolar distribution, a benthic habitat, and some level of genetic structure indicated by phylogeographical investigation. The purpose of this perspective piece is to set out an ecological genetics method to help resolve when the West Antarctic Ice Shelf last collapsed.

  8. Vapour and air bubble collapse analysis in viscous compressible water

    Directory of Open Access Journals (Sweden)

    Gil Bazanini

    2001-01-01

    Full Text Available Numerical simulations of the collapse of bubbles (or cavities are shown, using the finite difference method, taking into account the compressibility of the liquid, expected to occur in the final stages of the collapse process. Results are compared with experimental and theoretical data for incompressible liquids, to see the influence of the compressibility of the water in the bubble collapse. Pressure fields values are calculated in an area of 800 x 800 mm, for the case of one bubble under the hypothesis of spherical symmetry. Results are shown as radius versus time curves for the collapse (to compare collapse times, and pressure curves in the plane, for pressure fields. Such calculations are new because of their general point of view, since the existing works do not take into account the existence of vapour in the bubble, neither show the pressure fields seen here. It is also expected to see the influence of the compressibility of the water in the collapse time, and in the pressure field, when comparing pressure values.

  9. Characterization of the Dynamics of Vapor Bubble Collapse

    Science.gov (United States)

    Bardia, Raunak; Trujillo, Mario

    2017-11-01

    A numerical/theoretical analysis is presented to characterize the dynamics of a spherical vapor bubble, collapsing at different degrees of severity, controlled and quantified by the nondimensional number, B (introduced by Florschuetz and Chao, 1965). The numerical framework is exercised and validated over the three regimes of bubble collapse, namely, thermal, intermediate, and inertial collapse in increasing order of B. The conventional Rayleigh-Plesset perspective used to discriminate between different regimes, is extended to include the bubble energy balance and jump conditions. It is discovered that the time history of vapor velocity more clearly illustrates the distinctions between the three regimes. For thermal collapse, vapor velocity suffers an initial transient and then equilibrates to nearly zero. At intermediate rates of collapse, the time scales of the process are such that an imbalance occurs between the condensation rate and interface regression rate, which results in a significant magnitude of vapor velocity. At even larger rates of collapse, the time scales become exceedingly small such that the thermal boundary layer is sufficiently thin to provide the necessary heat conduction to balance the large condensation rate, resulting in negligible vapor velocity. National Science Foundation.

  10. Antibiotic susceptibility of Atopobium vaginae

    Directory of Open Access Journals (Sweden)

    Verschraegen Gerda

    2006-03-01

    Full Text Available Abstract Background Previous studies have indicated that a recently described anaerobic bacterium, Atopobium vaginae is associated with bacterial vaginosis (BV. Thus far the four isolates of this fastidious micro-organism were found to be highly resistant to metronidazole and susceptible for clindamycin, two antibiotics preferred for the treatment of BV. Methods Nine strains of Atopobium vaginae, four strains of Gardnerella vaginalis, two strains of Lactobacillus iners and one strain each of Bifidobacterium breve, B. longum, L. crispatus, L. gasseri and L. jensenii were tested against 15 antimicrobial agents using the Etest. Results All nine strains of A. vaginae were highly resistant to nalidixic acid and colistin while being inhibited by low concentrations of clindamycin (range: G. vaginalis strains were also susceptible for clindamycin ( 256 μg/ml but susceptible to clindamycin (0.023 – 0.125 μg/ml. Conclusion Clindamycin has higher activity against G. vaginalis and A. vaginae than metronidazole, but not all A. vaginae isolates are metronidazole resistant, as seemed to be a straightforward conclusion from previous studies on a more limited number of strains.

  11. Investigation of fire-induced collapse scenarios for a steel high-rise building

    DEFF Research Database (Denmark)

    Gentili, Filippo; Giuliani, Luisa; Bontempi, Franco

    2011-01-01

    The paper deals with the problem of understanding and evaluating the structural response of steel buildings to fire and outlines a general framework for the structural fire safety design of high-rise building. Among all building typology, the fire design of high-rise buildings is particularly...... (architectural design choices and active measures) and won’t be investigated in detail in this paper; the paper focus instead on structural design aspects, with specific reference to the iii) enhanced susceptibility of high-rise buildings to disproportionate collapse, due to the significant vertical elevation...... still a relatively low temperature at the time of failure: in this respect, the example of a high rise building is presented in the paper, where, depending on the fire scenarios considered and as different beam-column stiffness ratio, fire damages can remain localized to the heated zone or involve other...

  12. Characterizing ground motions that collapse steel special moment-resisting frames or make them unrepairable

    Science.gov (United States)

    Olsen, Anna H.; Heaton, Thomas H.; Hall, John F.

    2015-01-01

    This work applies 64,765 simulated seismic ground motions to four models each of 6- or 20-story, steel special moment-resisting frame buildings. We consider two vector intensity measures and categorize the building response as “collapsed,” “unrepairable,” or “repairable.” We then propose regression models to predict the building responses from the intensity measures. The best models for “collapse” or “unrepairable” use peak ground displacement and velocity as intensity measures, and the best models predicting peak interstory drift ratio, given that the frame model is “repairable,” use spectral acceleration and epsilon (ϵ) as intensity measures. The more flexible frame is always more likely than the stiffer frame to “collapse” or be “unrepairable.” A frame with fracture-prone welds is substantially more susceptible to “collapse” or “unrepairable” damage than the equivalent frame with sound welds. The 20-story frames with fracture-prone welds are more vulnerable to P-delta instability and have a much higher probability of collapse than do any of the 6-story frames.

  13. Finite element analysis of the collapse and post-collapse behavior of steel pipes applications to the oil industry

    CERN Document Server

    Dvorkin, Eduardo N

    2013-01-01

    This book presents a detailed discussion of the models that were developed to simulate the collapse and post-collapse behavior of steel pipes. The finite element method offers to engineers the possibility of developing models to simulate the collapse behavior of casings inside oil wells and the collapse behavior of deepwater pipelines. However, if technological decisions are going to be reached from these model results, with implications for the economic success of industrial operations, for the occupational safety and health and for the environment, the engineering models need to be highly reliable. Using these models engineers can quantify the effect of manufacturing tolerances, wear, corrosion, etc. This book describes in great details the experimental programs that are developed to validate the numerical results.

  14. Changes in magma storage conditions following caldera collapse at Okataina Volcanic Center, New Zealand

    Science.gov (United States)

    Rubin, Allison; Cooper, Kari M.; Leever, Marissa; Wimpenny, Josh; Deering, Chad; Rooney, Tyrone; Gravley, Darren; Yin, Qing-zhu

    2016-01-01

    Large silicic volcanic centers produce both small rhyolitic eruptions and catastrophic caldera-forming eruptions. Although changes in trace element and isotopic compositions within eruptions following caldera collapse have been observed at rhyolitic volcanic centers such as Yellowstone and Long Valley, much still remains unknown about the ways in which magma reservoirs are affected by caldera collapse. We present 238U-230Th age, trace element, and Hf isotopic data from individual zircon crystals from four eruptions from the Okataina Volcanic Center, Taupo Volcanic Zone, New Zealand, in order to assess changes in trace element and isotopic composition of the reservoir following the 45-ka caldera-forming Rotoiti eruption. Our data indicate that (1) mixing of magmas derived from crustal melts and mantle melts takes place within the shallow reservoir; (2) while the basic processes of melt generation likely did not change significantly between pre- and post-caldera rhyolites, post-caldera zircons show increased trace element and isotopic heterogeneity that suggests a decrease in the degree of interconnectedness of the liquid within the reservoir following collapse; and (3) post-caldera eruptions from different vents indicate different storage times of the amalgamated melt prior to eruption. These data further suggest that the timescales needed to generate large volumes of eruptible melt may depend on the timescales needed to increase interconnectedness and achieve widespread homogenization throughout the reservoir.

  15. Wetland succession in a permafrost collapse: interactions between fire and thermokarst

    Directory of Open Access Journals (Sweden)

    I. H. Myers-Smith

    2008-09-01

    Full Text Available To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate ~600 years of vegetation succession with a transition from a terrestrial forest to a sedge-dominated wetland over 100 years ago, and to a Sphagnum-dominated peatland in approximately 1970. The shift from sedge to Sphagnum, and a decrease in the detrended tree-ring width index of black spruce trees adjacent to the collapse coincided with an increase in the growing season temperature record from Fairbanks. This concurrent wetland succession and reduced growth of black spruce trees indicates a step-wise ecosystem-level response to a change in regional climate. In 2001, fire was observed coincident with permafrost collapse and resulted in lateral expansion of the peatland. These observations and the peat profile suggest that future warming and/or increased fire disturbance could promote permafrost degradation, peatland expansion, and increase carbon storage across this landscape; however, the development of drought conditions could reduce the success of both black spruce and Sphagnum, and potentially decrease the long-term ecosystem carbon storage.

  16. The Evolution of Juventae Chasma, Valles Marineris, Mars: Progressive Collapse and Sedimentation

    Science.gov (United States)

    Fueten, F.; Novakovic, N.; Stesky, R.; Flahaut, J.; Hauber, E.; Rossi, A. P.

    2017-11-01

    Juventae Chasma is an isolated chasm located north of the interconnected chasms within Valles Marineris. It contains four separate interior layered deposit (ILD) mounds. We have combined layer measurements, as well as mineralogical data of the mounds with topographic data of the remaining chasm and the surrounding plateau. Our observations indicate that the chasm underwent a complex geological history. We suggest that individual ILD mounds are not contemporaneous with each other and a series of progressive collapses enlarged an initially smaller chasm to its current shape. ILDs were deposited in a lacustrine setting, and the time of ILD deposition was limited. Basin collapse and chasm enlargement continued beyond the time of ILD deposition and thus were not driven by sediment load. Glacial processes appear to have played a role in the late, postlacustrine history of the chasm. We present a simplified model that highlights some of the complexity of the chasm evolution, but acknowledge that the true history is undoubtedly more complicated.

  17. Climate change and the population collapse during the “Great Famine” in pre-industrial Europe

    Science.gov (United States)

    Lima, Mauricio

    2014-01-01

    Population dynamics, economy, and human demography started with Malthus, the idea that population growth is limited by resources and “positive checks” occur when population growth overshoots the available resources. In fact, historical evidence indicates that long-term climate changes have destabilized civilizations and caused population collapses via food shortages, diseases, and wars. One of the worst population collapses of human societies occurred during the early fourteenth century in northern Europe; the “Great Famine” was the consequence of the dramatic effects of climate deterioration on human population growth. Thus, part of my motivation was to demonstrate that simple theoretical-based models can be helpful in understanding the causes of population change in preindustrial societies. Here, the results suggest that a logistic model with temperature as a “lateral” perturbation effect is the key element for explaining the population collapse exhibited by the European population during the “Great Famine”. PMID:24558584

  18. Steroid-associated hip joint collapse in bipedal emus.

    Directory of Open Access Journals (Sweden)

    Li-Zhen Zheng

    Full Text Available In this study we established a bipedal animal model of steroid-associated hip joint collapse in emus for testing potential treatment protocols to be developed for prevention of steroid-associated joint collapse in preclinical settings. Five adult male emus were treated with a steroid-associated osteonecrosis (SAON induction protocol using combination of pulsed lipopolysaccharide (LPS and methylprednisolone (MPS. Additional three emus were used as normal control. Post-induction, emu gait was observed, magnetic resonance imaging (MRI was performed, and blood was collected for routine examination, including testing blood coagulation and lipid metabolism. Emus were sacrificed at week 24 post-induction, bilateral femora were collected for micro-computed tomography (micro-CT and histological analysis. Asymmetric limping gait and abnormal MRI signals were found in steroid-treated emus. SAON was found in all emus with a joint collapse incidence of 70%. The percentage of neutrophils (Neut % and parameters on lipid metabolism significantly increased after induction. Micro-CT revealed structure deterioration of subchondral trabecular bone. Histomorphometry showed larger fat cell fraction and size, thinning of subchondral plate and cartilage layer, smaller osteoblast perimeter percentage and less blood vessels distributed at collapsed region in SAON group as compared with the normal controls. Scanning electron microscope (SEM showed poor mineral matrix and more osteo-lacunae outline in the collapsed region in SAON group. The combination of pulsed LPS and MPS developed in the current study was safe and effective to induce SAON and deterioration of subchondral bone in bipedal emus with subsequent femoral head collapse, a typical clinical feature observed in patients under pulsed steroid treatment. In conclusion, bipedal emus could be used as an effective preclinical experimental model to evaluate potential treatment protocols to be developed for prevention of

  19. On The Plausibility of The Gravitational Collapse As Driving Mechanism For Tectonic Extension

    Science.gov (United States)

    Viti, M.; Mantovani, E.; Albarello, D.

    normal geotherm, or greater than 15 km, whit a hot geotherm. The above results indicate that the gravitational collapse of a thickened belt may only oc- cur in fairly peculiar thermal/structural contexts, as the occurrence of high heat flow in an orogenic zone. In particular, the conditions required by gravitational collapse does not seem to be fulfilled in a number of zones, as some Mediterranean orogens, where this kind of tectonic process has been proposed as the driving mechanism of back arc extension.

  20. Cyclic eruptions and sector collapses at Monowai submarine volcano, Kermadec arc: 1998-2007

    Science.gov (United States)

    Chadwick, W. W.; Wright, I. C.; Schwarz-Schampera, U.; Hyvernaud, O.; Reymond, D.; de Ronde, C. E. J.

    2008-10-01

    Repeated multibeam bathymetric surveys at Monowai Cone, a shallow submarine basaltic volcano and part of the Monowai Volcanic Center in the northern Kermadec arc, were conducted in 1998, 2004, and 2007. These surveys document dramatic depth changes at the volcano including negative changes up to -176 m from two sector collapses and positive changes up to +138 m from volcanic reconstruction near the summit and debris avalanche deposits downslope of the slide scars. One sector collapse occurred on the SE slope between 1998 and 2004 with a volume of ˜0.09 km3, and another occurred on the SW slope between 2004 and 2007 with a volume of ˜0.04 km3. The volume of positive depth change due to addition of volcanic material by eruption is of the same order: ˜0.05 km3 between 1998 and 2004 and ˜0.06 km3 between 2004 and 2007. During these time intervals, monitoring by the Polynesian Seismic Network detected frequent T wave swarms at Monowai, indicative of explosive eruptive activity every few months. An unusual T wave swarm on 24 May 2002 was previously interpreted as the collapse event between the 1998 and 2004 surveys, but no similarly anomalous T waves were detected between 2004 and 2007, probably because the Polynesian Seismic Network stations were acoustically shadowed from the second slide event. We interpret that the sector collapses on Monowai are caused by the unstable loading of fragmental erupted material on the summit and steep upper slopes of the volcano (>20°). Moreover, there appears to be a cyclic pattern in which recurrent eruptions oversteepen the cone and periodically lead to collapse events that transport volcaniclastic material downslope to the lower apron of the volcano. Volumetric rate calculations suggest that these two processes may be more or less in equilibrium. The repeated collapses at Monowai are relatively modest in volume (involving only 0.1-0.5% of the edifice volume), have occurred much more frequently than is estimated for larger debris

  1. Equation of state effects on gravitational waves from rotating core collapse

    Science.gov (United States)

    Richers, Sherwood; Ott, Christian D.; Abdikamalov, Ernazar; O'Connor, Evan; Sullivan, Chris

    2017-03-01

    Gravitational waves (GWs) generated by axisymmetric rotating collapse, bounce, and early postbounce phases of a galactic core-collapse supernova are detectable by current-generation gravitational wave observatories. Since these GWs are emitted from the quadrupole-deformed nuclear-density core, they may encode information on the uncertain nuclear equation of state (EOS). We examine the effects of the nuclear EOS on GWs from rotating core collapse and carry out 1824 axisymmetric general-relativistic hydrodynamic simulations that cover a parameter space of 98 different rotation profiles and 18 different EOS. We show that the bounce GW signal is largely independent of the EOS and sensitive primarily to the ratio of rotational to gravitational energy, T /|W | , and at high rotation rates, to the degree of differential rotation. The GW frequency (fpeak˜600 - 1000 Hz ) of postbounce core oscillations shows stronger EOS dependence that can be parametrized by the core's EOS-dependent dynamical frequency √{G ρ¯ c } . We find that the ratio of the peak frequency to the dynamical frequency fpeak/√{G ρc ¯ } follows a universal trend that is obeyed by all EOS and rotation profiles and that indicates that the nature of the core oscillations changes when the rotation rate exceeds the dynamical frequency. We find that differences in the treatments of low-density nonuniform nuclear matter, of the transition from nonuniform to uniform nuclear matter, and in the description of nuclear matter up to around twice saturation density can mildly affect the GW signal. More exotic, higher-density physics is not probed by GWs from rotating core collapse. We furthermore test the sensitivity of the GW signal to variations in the treatment of nuclear electron capture during collapse. We find that approximations and uncertainties in electron capture rates can lead to variations in the GW signal that are of comparable magnitude to those due to different nuclear EOS. This emphasizes the

  2. In vitro Phenotypic Antibiotic Susceptibility Profiles Of Food Indicator ...

    African Journals Online (AJOL)

    The Gram-negative bacteria from granulated sugar samples had 7.69% phenotypic resistance profiles while the Gram-negative bacteria from table salt samples had between 13.3% and 20.0% resistance profiles. The resistance profiles of Gram-positive bacteria from granulated sugar samples was between 8.0% and 19.0% ...

  3. Synorogenic collapse: a perspective from the middle crust, the proterozoic grenville orogen.

    Science.gov (United States)

    Mezger, K; VAN DER Pluijm, B A; Essene, E J; Halliday, A N

    1991-11-01

    Structural, petrological, and geochronological studies of the middle to late Proterozoic Grenville orogen in Ontario, Canada, indicate that a major extensional fault developed synchronously with late thrusting. This fault zone was initiated during peak metamorphism and extended into the crust to depths of at least 25 kilometers. The temporal and spatial relations among faulting, metamorphism, and regional compression indicate that synorogenic collapse initiated because the crust exceeded the maximum physiographic height and thickness that could be supported by its rheology. Comparison of Grenville with recent Himalayan orogenic activity suggests that during Proterozoic times physiographic height, crustal thickness, and crustal strength were similar to modern conditions in orogenic belts.

  4. A validated approach for modeling collapse of steel structures

    Science.gov (United States)

    Saykin, Vitaliy Victorovich

    A civil engineering structure is faced with many hazardous conditions such as blasts, earthquakes, hurricanes, tornadoes, floods, and fires during its lifetime. Even though structures are designed for credible events that can happen during a lifetime of the structure, extreme events do happen and cause catastrophic failures. Understanding the causes and effects of structural collapse is now at the core of critical areas of national need. One factor that makes studying structural collapse difficult is the lack of full-scale structural collapse experimental test results against which researchers could validate their proposed collapse modeling approaches. The goal of this work is the creation of an element deletion strategy based on fracture models for use in validated prediction of collapse of steel structures. The current work reviews the state-of-the-art of finite element deletion strategies for use in collapse modeling of structures. It is shown that current approaches to element deletion in collapse modeling do not take into account stress triaxiality in vulnerable areas of the structure, which is important for proper fracture and element deletion modeling. The report then reviews triaxiality and its role in fracture prediction. It is shown that fracture in ductile materials is a function of triaxiality. It is also shown that, depending on the triaxiality range, different fracture mechanisms are active and should be accounted for. An approach using semi-empirical fracture models as a function of triaxiality are employed. The models to determine fracture initiation, softening and subsequent finite element deletion are outlined. This procedure allows for stress-displacement softening at an integration point of a finite element in order to subsequently remove the element. This approach avoids abrupt changes in the stress that would create dynamic instabilities, thus making the results more reliable and accurate. The calibration and validation of these models are

  5. Bubble Proliferation in Shock Wave Lithotripsy Occurs during Inertial Collapse

    Science.gov (United States)

    Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Williams, James C.; Bailey, Michael R.; Sapozhnikov, Oleg A.

    2008-06-01

    In shock wave lithotripsy (SWL), firing shock pulses at slow pulse repetition frequency (0.5 Hz) is more effective at breaking kidney stones than firing shock waves (SWs) at fast rate (2 Hz). Since at fast rate the number of cavitation bubbles increases, it appears that bubble proliferation reduces the efficiency of SWL. The goal of this work was to determine the basis for bubble proliferation when SWs are delivered at fast rate. Bubbles were studied using a high-speed camera (Imacon 200). Experiments were conducted in a test tank filled with nondegassed tap water at room temperature. Acoustic pulses were generated with an electromagnetic lithotripter (DoLi-50). In the focus of the lithotripter the pulses consisted of a ˜60 MPa positive-pressure spike followed by up to -8 MPa negative-pressure tail, all with a total duration of about 7 μs. Nonlinear propagation steepened the shock front of the pulses to become sufficiently thin (˜0.03 μm) to impose differential pressure across even microscopic bubbles. High-speed camera movies showed that the SWs forced preexisting microbubbles to collapse, jet, and break up into daughter bubbles, which then grew rapidly under the negative-pressure phase of the pulse, but later coalesced to re-form a single bubble. Subsequent bubble growth was followed by inertial collapse and, usually, rebound. Most, if not all, cavitation bubbles emitted micro-jets during their first inertial collapse and re-growth. After jetting, these rebounding bubbles could regain a spherical shape before undergoing a second inertial collapse. However, either upon this second inertial collapse, or sometimes upon the first inertial collapse, the rebounding bubble emerged from the collapse as a cloud of smaller bubbles rather than a single bubble. These daughter bubbles could continue to rebound and collapse for a few cycles, but did not coalesce. These observations show that the positive-pressure phase of SWs fragments preexisting bubbles but this initial

  6. Einstein-Cartan gravitational collapse of a homogeneous Weyssenhoff fluid

    Energy Technology Data Exchange (ETDEWEB)

    Ziaie, Amir Hadi; Sepangi, Hamid Reza [Shahid Beheshti University, Department of Physics, Tehran (Iran, Islamic Republic of); Vargas Moniz, Paulo [Universidade da Beira Interior, Departamento de Fisica, Covilha (Portugal); Universidade da Beira Interior, Centro de Matematica e Aplicacoes (CMA-UBI), Covilha (Portugal); Ranjbar, Arash [Shahid Beheshti University, Department of Physics, Tehran (Iran, Islamic Republic of); Centro de Estudios Cientficos (CECs), Valdivia (Chile); Universidad Andres Bello, Santiago (Chile)

    2014-11-15

    We consider the gravitational collapse of a spherically symmetric homogeneous matter distribution consisting of a Weyssenhoff fluid in the presence of a negative cosmological constant. Our aim is to investigate the effects of torsion and spin averaged terms on the final outcome of the collapse. For a specific interior space-time setup, namely the homogeneous and isotropic FLRW metric, we obtain two classes of solutions to the field equations where depending on the relation between spin source parameters, (i) the collapse procedure culminates in a space-time singularity or (ii) it is replaced by a non-singular bounce. We show that, under certain conditions, for a specific subset of the former solutions, the formation of trapped surfaces is prevented and thus the resulted singularity could be naked. The curvature singularity that forms could be gravitationally strong in the sense of Tipler. Our numerical analysis for the latter solutions shows that the collapsing dynamical process experiences four phases, so that two of which occur at the pre-bounce and the other two at post-bounce regimes. We further observe that there can be found a minimum radius for the apparent horizon curve, such that the main outcome of which is that there exists an upper bound for the size of the collapsing body, below which no horizon forms throughout the whole scenario. (orig.)

  7. SIGNATURES OF STAR CLUSTER FORMATION BY COLD COLLAPSE

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsova, Aleksandra; Hartmann, Lee [Department of Astronomy, University of Michigan, 1085 S. University Ave., Ann Arbor, MI 48109 (United States); Ballesteros-Paredes, Javier, E-mail: kuza@umich.edu [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Apdo. Postal 72-3 (Xangari), Morelia, Michocán 58089, México (Mexico)

    2015-12-10

    Subvirial gravitational collapse is one mechanism by which star clusters may form. Here we investigate whether this mechanism can be inferred from observations of young clusters. To address this question, we have computed smoothed particle hydrodynamics simulations of the initial formation and evolution of a dynamically young star cluster through cold (subvirial) collapse, starting with an ellipsoidal, turbulently seeded distribution of gas, and forming sink particles representing (proto)stars. While the initial density distributions of the clouds do not have large initial mass concentrations, gravitational focusing due to the global morphology leads to cluster formation. We use the resulting structures to extract observable morphological and kinematic signatures for the case of subvirial collapse. We find that the signatures of the initial conditions can be erased rapidly as the gas and stars collapse, suggesting that kinematic observations need to be made early in cluster formation and/or at larger scales, away from the growing cluster core. Our results emphasize that a dynamically young system is inherently evolving on short timescales, so that it can be highly misleading to use current-epoch conditions to study aspects such as star formation rates as a function of local density. Our simulations serve as a starting point for further studies of collapse including other factors such as magnetic fields and stellar feedback.

  8. Reduction of excavation face collapse risk in tunnelling.

    Science.gov (United States)

    Ariani, Filippo; Baldasseroni, Alberto; Muller, Alessandro; Biffino, Marco; Matteucci, Alessandro

    2017-12-14

    Two large road tunnels, recently developed near Florence, showed instabilities of the excavation face which subsequently caused sixteen collapses. Due to the risk for workers' safety, the public authority for occupational health and safety (ASL) has monitored the failure rate and other background variables in order to assess the possible correlations between risk reductions, its own actions, and those of the various safety actors involved. To evaluate if the interventions carried out by the design team were able to reduce the risks of collapse and which of the ASL actions and/or which other factors were more effective in changing the attitudes of the parties involved, leading to a more expensive but safer project variant. After adoption of the second of two project variants, no more collapses were observed. No correlation was found between trend of ASL inspections and observed variation of collapse rate. Conversely, the adoption of strongly coercive measures and investigation reporting by local media coincided with periods of risk reduction, even if the low number of events does not allow for statistical evaluation. These findings appear to be coherent with the ratio of the cost of penalties related to health and safety infringements (thousands of euros) to the overall cost of the safer project variant (a hundred times greater).  The safer variant required 7% more labour but avoided forced interruptions caused by the collapses, allowing a 13% faster excavation rate.

  9. Classical Collapse to Black Holes and Quantum Bounces: A Review

    Directory of Open Access Journals (Sweden)

    Daniele Malafarina

    2017-05-01

    Full Text Available In the last four decades, different programs have been carried out aiming at understanding the final fate of gravitational collapse of massive bodies once some prescriptions for the behaviour of gravity in the strong field regime are provided. The general picture arising from most of these scenarios is that the classical singularity at the end of collapse is replaced by a bounce. The most striking consequence of the bounce is that the black hole horizon may live for only a finite time. The possible implications for astrophysics are important since, if these models capture the essence of the collapse of a massive star, an observable signature of quantum gravity may be hiding in astrophysical phenomena. One intriguing idea that is implied by these models is the possible existence of exotic compact objects, of high density and finite size, that may not be covered by an horizon. The present article outlines the main features of these collapse models and some of the most relevant open problems. The aim is to provide a comprehensive (as much as possible overview of the current status of the field from the point of view of astrophysics. As a little extra, a new toy model for collapse leading to the formation of a quasi static compact object is presented.

  10. Magnetic field dependence of the atomic collapse state in graphene

    Science.gov (United States)

    Moldovan, D.; Ramezani Masir, M.; Peeters, F. M.

    2018-01-01

    Quantum electrodynamics predicts that heavy atoms (Z > Zc ≈ 170 ) will undergo the process of atomic collapse where electrons sink into the positron continuum and a new family of so-called collapsing states emerges. The relativistic electrons in graphene exhibit the same physics but at a much lower critical charge (Zc ≈ 1 ) which has made it possible to confirm this phenomenon experimentally. However, there exist conflicting predictions on the effect of a magnetic field on atomic collapse. These theoretical predictions are based on the continuum Dirac–Weyl equation, which does not have an exact analytical solution for the interplay of a supercritical Coulomb potential and the magnetic field. Approximative solutions have been proposed, but because the two effects compete on similar energy scales, the theoretical treatment varies depending on the regime which is being considered. These limitations are overcome here by starting from a tight-binding approach and computing exact numerical results. By avoiding special limit cases, we found a smooth evolution between the different regimes. We predict that the atomic collapse effect persists even after the magnetic field is activated and that the critical charge remains unchanged. We show that the atomic collapse regime is characterized: (1) by a series of Landau level anticrossings and (2) by the absence of \\sqrt{B} scaling of the Landau levels with regard to magnetic field strength.

  11. Preheating of the Intergalactic Medium by Gravitational Collapse and Ultraviolet Background

    Science.gov (United States)

    Zhu, Weishan; Feng, Long-Long

    2017-09-01

    The preheating of the intergalactic medium by structure collapse and ultraviolet background (UVB) is investigated in cosmological hydrodynamical simulations. When gravitational collapse is the sole heating mechanism, we find that (1) 60% and 45% of the IGM are heated up to S > 8 and 17 keV cm2, respectively, at z = 0, but the fractions drop rapidly to a few percent at z = 2 (2) the entropy of the circumhalo gas {S}{cir} is higher than the virial entropy for more than 75% of the halos with masses Mcooling time longer than the Hubble time {t}{cool,{cir}}> {t}{{H}} is merely 5%-10% at z≲ 0.5, and even less at z≥slant 1 for halos with M 17 {keV} {{cm}}2, but can increase the fraction of low-mass halos ( {S}{pr} to ˜70% at z = 0 and that having {t}{cool,{cir}}> {t}{{H}} to 15%-30% at z≲ 0.5. Our results indicate that preheating due to gravitational collapse and UVB is inadequate to fulfill the needs of the preventative model, especially for halos with {10}10.5 {M}⊙ conformity.

  12. Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica.

    Science.gov (United States)

    Rebesco, M; Domack, E; Zgur, F; Lavoie, C; Leventer, A; Brachfeld, S; Willmott, V; Halverson, G; Truffer, M; Scambos, T; Smith, J; Pettit, E

    2014-09-12

    Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf. Copyright © 2014, American Association for the Advancement of Science.

  13. Collapsing aged culture of the cyanobacterium Synechococcus elongatus produces compound(s toxic to photosynthetic organisms.

    Directory of Open Access Journals (Sweden)

    Assaf Cohen

    Full Text Available Phytoplankton mortality allows effective nutrient cycling, and thus plays a pivotal role in driving biogeochemical cycles. A growing body of literature demonstrates the involvement of regulated death programs in the abrupt collapse of phytoplankton populations, and particularly implicates processes that exhibit characteristics of metazoan programmed cell death. Here, we report that the cell-free, extracellular fluid (conditioned medium of a collapsing aged culture of the cyanobacterium Synechococcus elongatus is toxic to exponentially growing cells of this cyanobacterium, as well as to a large variety of photosynthetic organisms, but not to eubacteria. The toxic effect, which is light-dependent, involves oxidative stress, as suggested by damage alleviation by antioxidants, and the very high sensitivity of a catalase-mutant to the conditioned medium. At relatively high cell densities, S. elongatus cells survived the deleterious effect of conditioned medium in a process that required de novo protein synthesis. Application of conditioned medium from a collapsing culture caused severe pigment bleaching not only in S. elongatus cells, but also resulted in bleaching of pigments in a cell free extract. The latter observation indicates that the elicited damage is a direct effect that does not require an intact cell, and therefore, is mechanistically different from the metazoan-like programmed cell death described for phytoplankton. We suggest that S. elongatus in aged cultures are triggered to produce a toxic compound, and thus, this process may be envisaged as a novel regulated death program.

  14. Association between the capitate-triquetrum distance and carpal collapse in scaphoid nonunion.

    Science.gov (United States)

    Dimitriadis, Anastasios; Paraskevas, George; Kanavaros, Panagiotis; Barbouti, Alexandra; Vrettakos, Aristeidis; Kitsoulis, Panagiotis

    2015-03-01

    The effect of the lunate type on carpal collapse in cases of scaphoid nonunion has not been thoroughly investigated. The purpose of the present study was to determine whether any association exists or not between the capitate-triquetrum distance and occurrence of carpal collapse in cases of scaphoid nonunion. In a retrospective study, 76 patients with scaphoid nonunion formed two groups based on the capitate-triquetrum distance: forty-three patients with distance of less than 5 mm and 33 patients with distance of 5 mm or more. The two groups were comparable with respect to sex distribution, age, dominant hand involvement, manual labor, nonunion location and time from injury to final x-rays. Six patients (13.9%) in the capitate-triquetrum<5 mm group and 13 patients (39.4%) in the capitate-triquetrum≥5 mm group had no signs of collapse, with significant difference (p<0.05). Capitate-triquetrum distance could contribute in the decision making process for cases of scaphoid nonunion without straightforward indication for surgical intervention.

  15. Pineapple Fruit Collapse: Newly Emerging Disease of Pineapple Fruit in Lampung, Indonesia

    Directory of Open Access Journals (Sweden)

    Joko Prasetyo

    2014-03-01

    Full Text Available ABSTRACT Pineapple fruit collapse: newly emerging disease of pineapple fruit in Lampung, Indonesia Recently, a new disease on pineapple fruit has occurred in Lampung. Symptoms of the disease are complex. Fruits rotted and exuded copious liquid from the inter- fruitlet tissues accompanied by gas bubbles. Open spaces were formed inside the rotten fruit. Dissection of diseased fruit showed many cavities within its sceletal fibres and bad odour was exerted from the rotten tissues. A bacterial entity was isolated  from the diseased materials. In a pathogenicity test, the isolated bacteria caused the same symptom as mentioned. In the growing-on test the crown of the heavily infected fruit  showed  heart rot symptom.  Those  indicated that the disease was pineapple fruit collapse. Both symptoms were known related to the same causal agent, Erwinia chrysanthemi (pineapple strain Dickeya sp.. In our opinion, this is the first report of pineapple fruit collapse in Indonesia.

  16. Genetic susceptibility of periodontitis

    NARCIS (Netherlands)

    Laine, M.L.; Crielaard, W.; Loos, B.G.

    2012-01-01

    In this systematic review, we explore and summarize the peer-reviewed literature on putative genetic risk factors for susceptibility to aggressive and chronic periodontitis. A comprehensive literature search on the PubMed database was performed using the keywords ‘periodontitis’ or ‘periodontal

  17. Fourie susceptible.pmd

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    a number of cultivars exhibited field resistance to halo blight and bacterial brown spot, all cultivars were more or less susceptible to .... Cerillos. Alubia. I. 91. 57. Kranskop. Red speckled sugar. II. 97. 63. OPS-RS1. Red speckled sugar. II. 96. 63. OPS-RS2. Red speckled sugar. I. 100. 61. OPS-RS3. Red speckled sugar. II. 97.

  18. Unfolding of collapsed polymers in shear flow: effects of colloid banding structures in confining channels.

    Science.gov (United States)

    Chen, Hsieh; Alexander-Katz, Alfredo

    2014-03-01

    Using hydrodynamic simulations, we demonstrate that confined colloidal suspensions can greatly enhance the unfolding of collapsed single polymers in flow. When colloids come in direct contact with the polymers due to the flow, the collapsed chains become flattened or elongated on the surface of the colloids, increasing the probability of forming large chain protrusions that the flow can pull out to unfold the polymers. This phenomenon may be suppressed if the colloid size is commensurate with the confining channels, where the colloids form well-defined banding structures. Here, we analyze the colloid banding structures in detail and their relation to the chain unfolding. We find that for colloid volume fractions up to 30%, the confined colloids form simple cubic (sc), hexagonal (hex), or a mixture of sc + hex structures. By directly changing the heights of the confining channels, we show that the collapsed polymers unfold the most in the mixed sc + hex structures. The diffuse (not well-defined) bands in the mixed sc + hex structures provide the highest collision probability for the colloids and the polymers, thus enhancing unfolding the most. Without colloidal suspensions, we show that the confining channels alone do not have an observable effect on the unfolding of collapsed polymers. The well-defined colloid bands also suppress the unfolding of noncollapsed polymers. In fact, the average size for noncollapsed chains is even smaller in the well-defined bands than in a channel without any colloids. The appearance of well-defined bands in this case also indicates that lift forces experienced by the polymers in confinement are negligible compared to those exerted by the colloidal band structures. Our results may be important for understanding the dynamics of mixed colloid polymer solutions.

  19. High-mass Star Formation through Filamentary Collapse and Clump-fed Accretion in G22

    Science.gov (United States)

    Yuan, Jinghua; Li, Jin-Zeng; Wu, Yuefang; Ellingsen, Simon P.; Henkel, Christian; Wang, Ke; Liu, Tie; Liu, Hong-Li; Zavagno, Annie; Ren, Zhiyuan; Huang, Ya-Fang

    2018-01-01

    How mass is accumulated from cloud-scale down to individual stars is a key open question in understanding high-mass star formation. Here, we present the mass accumulation process in a hub-filament cloud G22 that is composed of four supercritical filaments. Velocity gradients detected along three filaments indicate that they are collapsing with a total mass infall rate of about 440 M ⊙ Myr‑1, suggesting the hub mass would be doubled in six free-fall times, adding up to ∼2 Myr. A fraction of the masses in the central clumps C1 and C2 can be accounted for through large-scale filamentary collapse. Ubiquitous blue profiles in HCO+ (3–2) and 13CO (3–2) spectra suggest a clump-scale collapse scenario in the most massive and densest clump C1. The estimated infall velocity and mass infall rate are 0.31 km s‑1 and 7.2 × 10‑4 M ⊙ yr‑1, respectively. In clump C1, a hot molecular core (SMA1) is revealed by the Submillimeter Array observations and an outflow-driving high-mass protostar is located at the center of SMA1. The mass of the protostar is estimated to be 11–15 M ⊙ and it is still growing with an accretion rate of 7 × 10‑5 M ⊙ yr‑1. The coexistent infall in filaments, clump C1, and the central hot core in G22 suggests that pre-assembled mass reservoirs (i.e., high-mass starless cores) may not be required to form high-mass stars. In the course of high-mass star formation, the central protostar, the core, and the clump can simultaneously grow in mass via core-fed/disk accretion, clump-fed accretion, and filamentary/cloud collapse.

  20. Collapse of magnetized hypermassive neutron stars in general relativity.

    Science.gov (United States)

    Duez, Matthew D; Liu, Yuk Tung; Shapiro, Stuart L; Shibata, Masaru; Stephens, Branson C

    2006-01-27

    Hypermassive neutron stars (HMNSs)--equilibrium configurations supported against collapse by rapid differential rotation--are possible transient remnants of binary neutron-star mergers. Using newly developed codes for magnetohydrodynamic simulations in dynamical spacetimes, we are able to track the evolution of a magnetized HMNS in full general relativity for the first time. We find that secular angular momentum transport due to magnetic braking and the magnetorotational instability results in the collapse of an HMNS to a rotating black hole, accompanied by a gravitational wave burst. The nascent black hole is surrounded by a hot, massive torus undergoing quasistationary accretion and a collimated magnetic field. This scenario suggests that HMNS collapse is a possible candidate for the central engine of short gamma-ray bursts.

  1. Gravitational collapse to a Kerr-Newman black hole

    Science.gov (United States)

    Nathanail, Antonios; Most, Elias R.; Rezzolla, Luciano

    2017-07-01

    We present the first systematic study of the gravitational collapse of rotating and magnetized neutron stars to charged and rotating (Kerr-Newman) black holes. In particular, we consider the collapse of magnetized and rotating neutron stars assuming that no pair-creation takes place and that the charge density in the magnetosphere is so low that the stellar exterior can be described as an electrovacuum. Under these assumptions, which are rather reasonable for a pulsar that has crossed the 'death line', we show that when the star is rotating, it acquires a net initial electrical charge, which is then trapped inside the apparent horizon of the newly formed back hole. We analyse a number of different quantities to validate that the black hole produced is indeed a Kerr-Newman one and show that, in the absence of rotation or magnetic field, the end result of the collapse is a Schwarzschild or Kerr black hole, respectively.

  2. Improved Noninterferometric Test of Collapse Models Using Ultracold Cantilevers

    Science.gov (United States)

    Vinante, A.; Mezzena, R.; Falferi, P.; Carlesso, M.; Bassi, A.

    2017-09-01

    Spontaneous collapse models predict that a weak force noise acts on any mechanical system, as a consequence of the collapse of the wave function. Significant upper limits on the collapse rate have been recently inferred from precision mechanical experiments, such as ultracold cantilevers and the space mission LISA Pathfinder. Here, we report new results from an experiment based on a high-Q cantilever cooled to millikelvin temperatures, which is potentially able to improve the current bounds on the continuous spontaneous localization (CSL) model by 1 order of magnitude. High accuracy measurements of the cantilever thermal fluctuations reveal a nonthermal force noise of unknown origin. This excess noise is compatible with the CSL heating predicted by Adler. Several physical mechanisms able to explain the observed noise have been ruled out.

  3. Gravitational collapse of thin shells of dust in Shape Dynamics

    CERN Document Server

    Gomes, Henrique; Mercati, Flavio; Napoletano, Andrea

    2015-01-01

    Shape dynamics is a theory of gravity whose physical configuration space is composed of spatial conformal equivalence classes of 3-dimensional geometries. This physical configuration space is not a priori related to the one given by 4-dimensional space-time geometries, familiar to general relativists. Although one can largely match dynamical solutions arising in each theory, this is not always the case. One expects such differences in collapse situations that lead to the formation of black holes. In this paper we study spherical collapse of thin-shells of pressureless dust as a fully back-reacting dynamical system, in a context related to both shape dynamics and general relativity in ADM form in Constant Mean Curvature (CMC) gauge -- the particular time slicing where any correspondence between ADM and shape dynamics is manifest. To better accommodate the relational setting of shape dynamics, we also begin a study of collapse of two such shells in a compact Universe.

  4. Gravitational collapse of a magnetized fermion gas with finite temperature

    Energy Technology Data Exchange (ETDEWEB)

    Delgado Gaspar, I. [Instituto de Geofisica y Astronomia (IGA), La Habana (Cuba); Perez Martinez, A. [Instituto de Cibernetica, Matematica y Fisica (ICIMAF), La Habana (Cuba); Sussman, Roberto A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (ICN-UNAM), Mexico (Mexico); Ulacia Rey, A. [Instituto de Cibernetica, Matematica y Fisica (ICIMAF), La Habana (Cuba); Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (ICN-UNAM), Mexico (Mexico)

    2013-07-15

    We examine the dynamics of a self-gravitating magnetized fermion gas at finite temperature near the collapsing singularity of a Bianchi-I spacetime. Considering a general set of appropriate and physically motivated initial conditions, we transform Einstein-Maxwell field equations into a complete and self-consistent dynamical system amenable for numerical work. The resulting numerical solutions reveal the gas collapsing into both, isotropic (''point-like'') and anisotropic (''cigar-like''), singularities, depending on the initial intensity of the magnetic field. We provide a thorough study of the near collapse behavior and interplay of all relevant state and kinematic variables: temperature, expansion scalar, shear scalar, magnetic field, magnetization, and energy density. A significant qualitative difference in the behavior of the gas emerges in the temperature range T/m{sub f} {proportional_to} 10{sup -6} and T/m{sub f} {proportional_to} 10{sup -3}. (orig.)

  5. Exploring an S-matrix for gravitational collapse

    CERN Document Server

    Veneziano, Gabriele

    2008-01-01

    We analyze further a recently proposed S-matrix description of transplanckian scattering in the specific case of axisymmetric collisions of extended sources, where some of the original approximations are not necessary. We confirm the claim that such an approximate description appears to capture the essential features of (the quantum counterpart of) classical gravitational collapse. More specifically, the S-matrix develops singularities whose location in the sources' parameter space are consistent with (and numerically close to) the bounds coming from closed-trapped-surface collapse criteria. In the vicinity of the critical "lines" the phase of the elastic S-matrix exhibits a universal fractional-power behaviour reminiscent of Choptuik's scaling near critical collapse.

  6. Magnetorotatioal Collapse of Supermassive Stars: Black Hole Formation and Jets

    Science.gov (United States)

    Sun, Lunan; Paschalidis, Vasileios; Ruiz, Milton; Shapiro, Stuart

    2017-01-01

    We perform magnetohydrodynamic simulations in full general relativity of the collapse of radially unstable, uniformly rotating, massive stars to black holes. The stars spin at the mass-shedding limit, account for magnetic fields and obey a Γ = 4/3 EOS. The calculations lift the restriction of axisymmetry imposed in previous simulations. Our simulations model the direct collapse of supermassive stars to supermassive BHs (>=104M⊙) at high cosmological redshifts, which may explain the appearance of supermassive BHs and quasars by z 7. They also crudely model the collapse of massive Pop III stars to massive BHs, which could power some of the long gamma-ray bursts observed by FERMI and SWIFT at z 6-8. We analyze the properties of the electromagnetic and gravitational wave signatures of these events and discuss the detectability of such multimessenger sources.

  7. Evidence of Multiple Flank Collapse at Volcan Baru, Panama

    Science.gov (United States)

    Herrick, J. A.; Rose, W. I.

    2009-12-01

    Michigan Tech's Peace Corps Master's International program (PCMI) in Geological Hazards has enabled several long-term investigations of active volcanoes in Latin America. To contribute to volcanic hazard assessments in Panama and achieve the goals defined by the PCMI program, we developed this debris avalanche project to address outstanding questions regarding Volcan Baru's most devastating event - massive slope failure of the western flank. Relying on basic mapping tools as well as the 2007 USGS Open-File Report focusing on hazard assessments of Panama's youngest and potentially active volcano, identification of the debris avalanche deposits (DAD) required detailed field investigations to determine the limits of the units. Extending across an area larger than 600 km2, field strategies were developed based on outcrop exposures within drainages and road-cuts. Aerial photos and DEMs of Baru's nested craters were interpreted by earlier scientists as the remains of two collapsed flanks. The results from in-depth field traverses provide several important discoveries: paleosols and sharp contacts within the stratigraphy indicate multiple DAD, deeply weathered hummocks red-flag the deposits more than 50-km away from Baru's crater, and high-quality radiocarbon samples (up to 45-cm long fragments of entrained wood) lie in the distal reaches of the debris flow area. During the 2008-2009 field seasons, we received assistance from the University of Panama, Civil Protection, and Panama's National Institute of Geography. Support from local experts and feedback from professional scientists of the Smithsonian Institution and Costa Rica's Institute of Electricity were invaluable. The 2-year investment in volcanic hazard studies has brought together resources from several countries as well as fresh data that will benefit the residents and emergency management officials of Panama. Jigsaw fractured clasts lie within Volcan Baru's debris avalanche deposits more than 28 km south of the

  8. Gravitational Collapse of Massless Fields in an Expanding Universe

    Directory of Open Access Journals (Sweden)

    Yoo Chul-Moon

    2018-01-01

    Full Text Available Gravitational collapse of a massless scalar field with the periodic boundary condition in a cubic box is reported. This system can be regarded as a lattice universe model. The initial data is constructed for a Gaussian like profile of the scalar field taking the integrability condition associated with the periodic boundary condition into account. For a large initial amplitude, a black hole is formed after a certain period of time. While the scalar field spreads out in the whole region for a small initial amplitude. The difference of the late time expansion law of the lattice universe depending on the final fate of the gravitational collapse is discussed.

  9. Gravitational Collapse of Massless Fields in an Expanding Universe

    Science.gov (United States)

    Yoo, Chul-Moon

    2018-01-01

    Gravitational collapse of a massless scalar field with the periodic boundary condition in a cubic box is reported. This system can be regarded as a lattice universe model. The initial data is constructed for a Gaussian like profile of the scalar field taking the integrability condition associated with the periodic boundary condition into account. For a large initial amplitude, a black hole is formed after a certain period of time. While the scalar field spreads out in the whole region for a small initial amplitude. The difference of the late time expansion law of the lattice universe depending on the final fate of the gravitational collapse is discussed.

  10. Collapse mechanisms and strength prediction of reinforced concrete pile caps

    DEFF Research Database (Denmark)

    Jensen, Uffe G.; Hoang, Linh Cao

    2012-01-01

    This paper describes an upper bound plasticity approach for strength prediction of reinforced concrete pile caps. A number of collapse mechanisms are identified and analysed. The procedure leads to an estimate of the load-carrying capacity and an identification of the critical collapse mechanism....... Calculations have been compared with nearly 200 test results found in the literature. Satisfactory agreement has been found. The analyses are conducted on concentrically loaded caps supported by four piles. The paper briefly outlines how the approach may be extended to more complicated loadings and geometries...

  11. Systematic Features and Progenitor Dependence of Core-Collapse Supernovae

    Science.gov (United States)

    Nakamura, Ko; Takiwaki, Tomoya; Kuroda, Takami; Kotake, Kei

    We present our latest results of two-dimensional core-collapse supernova simulations for about 400 progenitors. Our self-consistent supernova models reveal the systematic features of core-collapse supernova properties such as neutrino luminosity and energy spectrum, explosion energy, remnant mass, and yield of radioactive 56Ni. We find that these explosion characteristics tend to show a monotonic increase as a function of mass accretion rate onto a shock. The accretion rate depends on the structure of the progenitor core and its envelope, which is well described by the compactness parameter.

  12. Genetic Susceptibility to Atherosclerosis

    Directory of Open Access Journals (Sweden)

    Sanja Kovacic

    2012-01-01

    Full Text Available Atherosclerosis is a complex multifocal arterial disease involving interactions of multiple genetic and environmental factors. Advances in techniques of molecular genetics have revealed that genetic ground significantly influences susceptibility to atherosclerotic vascular diseases. Besides further investigations of monogenetic diseases, candidate genes, genetic polymorphisms, and susceptibility loci associated with atherosclerotic diseases have been identified in recent years, and their number is rapidly increasing. This paper discusses main genetic investigations fields associated with human atherosclerotic vascular diseases. The paper concludes with a discussion of the directions and implications of future genetic research in arteriosclerosis with an emphasis on prospective prediction from an early age of individuals who are predisposed to develop premature atherosclerosis as well as to facilitate the discovery of novel drug targets.

  13. Marijuana Usage and Hypnotic Susceptibility

    Science.gov (United States)

    Franzini, Louis R.; McDonald, Roy D.

    1973-01-01

    Anonymous self-reported drug usage data and hypnotic susceptibility scores were obtained from 282 college students. Frequent marijuana users (more than 10 times) showed greater susceptibility to hypnosis than nonusers. (Author)

  14. Waste indicators

    Energy Technology Data Exchange (ETDEWEB)

    Dall, O.; Lassen, C.; Hansen, E. [Cowi A/S, Lyngby (Denmark)

    2003-07-01

    The Waste Indicator Project focuses on methods to evaluate the efficiency of waste management. The project proposes the use of three indicators for resource consumption, primary energy and landfill requirements, based on the life-cycle principles applied in the EDIP Project. Trial runs are made With the indicators on paper, glass packaging and aluminium, and two models are identified for mapping the Danish waste management, of which the least extensive focuses on real and potential savings. (au)

  15. Quality indicators

    DEFF Research Database (Denmark)

    Hjorth-Andersen, Christian

    1991-01-01

    to the issue of how well these indicators perform, using market data provided by consumer magazines from 3 countries. The results strongly indicate that price is a poor quality indicator. The paper also presents some evidence which suggests that seller reputation and easily observable characteristics are also......In recent literature it has been suggested that consumers need have no knowledge of product quality as a number of quality indicators (or signals) may be used as substitutes. Very little attention has been paid to the empirical verification of these studies. The present paper is devoted...

  16. The Aging Kidney: Increased Susceptibility to Nephrotoxicity

    Directory of Open Access Journals (Sweden)

    Xinhui Wang

    2014-09-01

    Full Text Available Three decades have passed since a series of studies indicated that the aging kidney was characterized by increased susceptibility to nephrotoxic injury. Data from these experimental models is strengthened by clinical data demonstrating that the aging population has an increased incidence and severity of acute kidney injury (AKI. Since then a number of studies have focused on age-dependent alterations in pathways that predispose the kidney to acute insult. This review will focus on the mechanisms that are altered by aging in the kidney that may increase susceptibility to injury, including hemodynamics, oxidative stress, apoptosis, autophagy, inflammation and decreased repair.

  17. Prediction of the wetting-induced collapse behaviour using the soil-water characteristic curve

    Science.gov (United States)

    Xie, Wan-Li; Li, Ping; Vanapalli, Sai K.; Wang, Jia-Ding

    2018-01-01

    Collapsible soils go through three distinct phases in response to matric suction decrease during wetting: pre-collapse phase, collapse phase and post-collapse phase. It is reasonable and conservative to consider a strain path that includes a pre-collapse phase in which constant volume is maintained and a collapse phase that extends to the final matric suction to be experienced by collapsible soils during wetting. Upon this assumption, a method is proposed for predicting the collapse behaviour due to wetting. To use the proposed method, two parameters, critical suction and collapse rate, are required. The former is the suction value below which significant collapse deformations take place in response to matric suction decease, and the later is the rate at which void ratio reduces with matric suction in the collapse phase. The value of critical suction can be estimated from the water-entry value taking account of both the microstructure characteristics and collapse mechanism of fine-grained collapsible soils; the wetting soil-water characteristic curve thus can be used as a tool. Five sets of data of wetting tests on both compacted and natural collapsible soils reported in the literature were used to validate the proposed method. The critical suction values were estimated from the water-entry value with parameter a that is suggested to vary between 0.10 and 0.25 for compacted soils and to be lower for natural collapsible soils. The results of a field permeation test in collapsible loess soils were also used to validate the proposed method. The relatively good agreement between the measured and estimated collapse deformations suggests that the proposed method can provide reasonable prediction of the collapse behaviour due to wetting.

  18. Geophysical Assessment of Two Collapsed and Concealed Septic ...

    African Journals Online (AJOL)

    A geophysical study was carried out in the vicinity of two collapsed and concealed septic tanks to delineate the structures responsible for their failure. Two-dimensional resistivity and seismic refraction tomography data were collected along a profile laid across the septic tanks. The data were collected using ABEM ...

  19. Explosion of a collapsing Bose-Einstein condensate

    NARCIS (Netherlands)

    Duine, R.A.; Stoof, H.T.C.

    2001-01-01

    We show that elastic collisions between atoms in a Bose-Einstein condensate with attractive interactions can lead to an explosion that ejects a large fraction of the collapsing condensate. We study variationally the dynamics of this explosion and find excellent agreement with recent experiments on

  20. Explosion of a Collapsing Bose-Einstein Condensate

    NARCIS (Netherlands)

    Duine, R.A.; Stoof, H.T.C.

    2000-01-01

    we show that elastic collisions between atoms in an Bose-Einstein condensate with attractive interactions lead to an explosion that ejects a large fraction of the collapsing condensate. We study variationally the dynamics of thes explosion and find excellent agreement with recent experiments on

  1. Deconvolution of acoustically detected bubble-collapse shock waves.

    Science.gov (United States)

    Johansen, Kristoffer; Song, Jae Hee; Johnston, Keith; Prentice, Paul

    2017-01-01

    The shock wave emitted by the collapse of a laser-induced bubble is detected at propagation distances of 30, 40and50mm, using a PVdF needle hydrophone, with a non-flat end-of-cable frequency response, calibrated for magnitude and phase, from 125kHz to 20MHz. High-speed shadowgraphic imaging at 5×106 frames per second, 10nstemporal resolution and 256 frames per sequence, records the bubble deflation from maximum to minimum radius, the collapse and shock wave generation, and the subsequent rebound in unprecedented detail, for a single sequence of an individual bubble. The Gilmore equation for bubble oscillation is solved according to the resolved bubble collapse, and simulated shock wave profiles deduced from the acoustic emissions, for comparison to the hydrophone recordings. The effects of single-frequency calibration, magnitude-only and full waveform deconvolution of the experimental data are presented, in both time and frequency domains. Magnitude-only deconvolution increases the peak pressure amplitude of the measured shock wave by approximately 9%, from single-frequency calibration, with full waveform deconvolution increasing it by a further 3%. Full waveform deconvolution generates a shock wave profile that is in agreement with the simulated profile, filtered according to the calibration bandwidth. Implications for the detection and monitoring of acoustic cavitation, where the role of periodic bubble collapse shock waves has recently been realised, are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Reopening modes of a collapsed elasto-rigid channel

    CERN Document Server

    Ducloué, Lucie; Thompson, Alice B; Juel, Anne

    2016-01-01

    Motivated by the reopening mechanics of strongly collapsed airways, we study the steady propagation of an air finger through a collapsed oil-filled channel with a single compliant wall. In a previous study using fully-compliant elastic tubes, a `pointed' air finger was found to propagate at high speed and low pressure, which may enable rapid reopening of highly collapsed airways with minimal tissue damage (Heap & Juel 2008). In this paper, we identify the selection mechanism of that pointed finger, which remained unexplained, by conducting an experimental study in a rigid rectangular Hele-Shaw channel with an elastic top boundary. The constitutive behaviour of this elasto-rigid channel is broadly similar to that of an elastic tube, but unlike the tube the channel's cross-section adopts self-similar shapes from the undeformed state to the point of first near wall contact. The simplification of the vessel geometry enables the systematic investigation of the reopening dynamics in terms of initial collapse. W...

  3. A Collapsed Variational Bayesian Inference Algorithm for Latent Dirichlet Allocation

    Science.gov (United States)

    2007-09-07

    A Collapsed Variational Bayesian Inference Algorithm for Latent Dirichlet Allocation Yee Whye Teh Gatsby Computational Neuroscience Unit University...thesis, Gatsby Computa- tional Neuroscience Unit, University College London, 2003. [12] J. Sung, Z. Ghahramani, and S. Choi. Variational Bayesian EM: A

  4. Flow and oscillations in collapsible tubes: Physiological applications ...

    Indian Academy of Sciences (India)

    The motivation for this subject comes from physiology: Air-flow in the lungs, where flow limitation during forced expiration is a consequence of large-airway collapse, and wheezing, which is a manifestation of self-excited mechanical oscillations; Blood flow in veins, such as those of giraffes, in which the return of blood to the ...

  5. Gravitational Collapse and Structure Formation in an Expanding ...

    Indian Academy of Sciences (India)

    IAS Admin

    RESONANCE. September 2015. GENERAL ARTICLE. Gravitational Collapse and Structure Formation in an. Expanding Universe. J S Bagla and Pritpal Kaur Sandhu. Keywords. Cosmology, gravitational col- lapse, galaxy formation. (left) Jasjeet Bagla works at IISER Mohali. His research is mainly in the area of cosmology.

  6. Tunneling into microstate geometries: quantum effects stop gravitational collapse

    NARCIS (Netherlands)

    Bena, I.; Mayerson, D.R.; Puhm, A.; Vercnocke, B.

    Collapsing shells form horizons, and when the curvature is small classical general relativity is believed to describe this process arbitrarily well. On the other hand, quantum information theory based (fuzzball/firewall) arguments suggest the existence of some structure at the black hole horizon.

  7. An infrequent cause of total lung collapse: Endobronchial lipoma

    African Journals Online (AJOL)

    Fahd Ahmed Suhail

    2014-06-21

    Jun 21, 2014 ... Radiology;. Total lung collapse. Abstract Endobronchial lipomas are rare benign tumors of the lung. The reported case was a. 46-year-old man who came to our center for follow up of endobronchial ... 2014 Alexandria University Faculty of Medicine. ... attacks may induce sufficient nuclear atypia to suggest.

  8. Surviving a cluster collapse: risk aversion as a core value

    NARCIS (Netherlands)

    Schiele, Holger; Hospers, Gerrit J.; van der Zee, D.J.

    2012-01-01

    Purpose – This paper analyses firms, which survived in a collapsed regional cluster. The target is to analyze whether the principles for enduring success identified researching success factors of very old firms also apply in such an environment. Design/methodology/approach – The authors conduct a

  9. Explosive X-point collapse in relativistic magnetically dominated plasma

    Science.gov (United States)

    Lyutikov, Maxim; Sironi, Lorenzo; Komissarov, Serguei S.; Porth, Oliver

    2017-12-01

    The extreme properties of the gamma-ray flares in the Crab nebula present a clear challenge to our ideas on the nature of particle acceleration in relativistic astrophysical plasma. It seems highly unlikely that standard mechanisms of stochastic type are at work here and hence the attention of theorists has switched to linear acceleration in magnetic reconnection events. In this series of papers, we attempt to develop a theory of explosive magnetic reconnection in highly magnetized relativistic plasma which can explain the extreme parameters of the Crab flares. In the first paper, we focus on the properties of the X-point collapse. Using analytical and numerical methods (fluid and particle-in-cell simulations) we extend Syrovatsky's classical model of such collapse to the relativistic regime. We find that the collapse can lead to the reconnection rate approaching the speed of light on macroscopic scales. During the collapse, the plasma particles are accelerated by charge-starved electric fields, which can reach (and even exceed) values of the local magnetic field. The explosive stage of reconnection produces non-thermal power-law tails with slopes that depend on the average magnetization . For sufficiently high magnetizations and vanishing guide field, the non-thermal particle spectrum consists of two components: a low-energy population with soft spectrum that dominates the number census; and a high-energy population with hard spectrum that possesses all the properties needed to explain the Crab flares.

  10. Temperature considerations in numerical simulations of collapsing bubbles

    Science.gov (United States)

    Johnsen, Eric; Alahyari Beig, Shahaboddin

    2014-11-01

    In naval and biomedical engineering applications, the inertial collapse of cavitation bubbles is known to damage its surroundings. While significant attention has been dedicated to investigating the pressures produced by this process, less is known about heating of the surrounding medium, which may be important when collapse occurs near objects whose properties strongly depend on temperature (e.g., polymers). Euler simulations are capable of predicting the high pressures thereby generated. However, numerical errors can occur when solving the Navier-Stokes equations for compressible interface problems. Using a newly developed computational approach that prevents such errors, we investigate the dynamics of shock-induced and Rayleigh collapse of individual and collections of gas bubbles, in a free field and near rigid surfaces. We characterize the temperature rises based on the relevant non-dimensional parameters entering the problem. In particular, we show that the temperature of a neighboring object rises due to two mechanisms: the shock produced at collapse and heat diffusion from the hot bubble as it moves toward the object. This work was supported by ONR Grant N00014-12-1-0751.

  11. European Neolithic societies showed early warning signals of population collapse.

    Science.gov (United States)

    Downey, Sean S; Haas, W Randall; Shennan, Stephen J

    2016-08-30

    Ecosystems on the verge of major reorganization-regime shift-may exhibit declining resilience, which can be detected using a collection of generic statistical tests known as early warning signals (EWSs). This study explores whether EWSs anticipated human population collapse during the European Neolithic. It analyzes recent reconstructions of European Neolithic (8-4 kya) population trends that reveal regime shifts from a period of rapid growth following the introduction of agriculture to a period of instability and collapse. We find statistical support for EWSs in advance of population collapse. Seven of nine regional datasets exhibit increasing autocorrelation and variance leading up to collapse, suggesting that these societies began to recover from perturbation more slowly as resilience declined. We derive EWS statistics from a prehistoric population proxy based on summed archaeological radiocarbon date probability densities. We use simulation to validate our methods and show that sampling biases, atmospheric effects, radiocarbon calibration error, and taphonomic processes are unlikely to explain the observed EWS patterns. The implications of these results for understanding the dynamics of Neolithic ecosystems are discussed, and we present a general framework for analyzing societal regime shifts using EWS at large spatial and temporal scales. We suggest that our findings are consistent with an adaptive cycling model that highlights both the vulnerability and resilience of early European populations. We close by discussing the implications of the detection of EWS in human systems for archaeology and sustainability science.

  12. Spherical Domain Wall Collapse in a Dust Universe

    CERN Document Server

    Tanahashi, Norihiro

    2014-01-01

    To clarify observational consequence of bubble nucleations in inflationary era, we analyse dynamics of a spherical domain wall in an expanding universe. We consider a spherical shell of the domain wall with tension $\\sigma$ collapsing in a spherically-symmetric dust universe, which is initially separated into the open Friedmann-Lema\\^itre-Robertson-Walker universe inside the shell and the Einstein-de Sitter universe outside. The domain wall shell collapses due to the tension, and sweeps the dust fluid. The universe after the collapse becomes inhomogeneous and is described by the Lema\\^itre-Tolman-Bondi model. We construct solutions describing this inhomogeneous universe by solving dynamical equations obtained from Israel's junction conditions applied to this system. We find that a black hole forms after the domain wall collapse for any initial condition, and that the black hole mass at the moment of its formation is universally given by $M_{\\rm BH}\\simeq 17 \\sigma/H_{\\rm hc}$, where $H_{\\rm hc}$ is the Hubble...

  13. Cardiovascular collapse due to intravenous verapamil in two ...

    African Journals Online (AJOL)

    controlled with propranolol in one and sotalol in the other. Factors contributing to the cardiovascular collapse ... controlled for 8 months, during which the patient remained asymptomatic. Thereafter he returned to his home in ... decrease in cardiac output, cause marked hypotension. Circulatory arrest in patient 1 was due to ...

  14. Collapse of the roof of a football stadium

    NARCIS (Netherlands)

    Borsje, H.; Renier, B.; Burggraaf, H.G.

    2014-01-01

    In the summer of 2011 the Dutch football club FC Twente was building an extension of their stadium De Grolsch Veste, to increase the capacity of the stadium. On july 7th 2011, during construction, the roof of the partially finished extension collapsed. As a result of this accident two workers were

  15. Forensic collapse investigation of a concrete bridge with timber piers.

    Science.gov (United States)

    2009-04-01

    This report outlines the forensic investigation of the collapse of Bridge No. SN 019-5010 in DeKalb County, : Illinois on August 19, 2008. The bridge consisted of three 42 feet precast prestressed concrete deck beams : simply-supported by concrete pi...

  16. mode of collapse of square single panel reinforced concrete space

    African Journals Online (AJOL)

    eobe

    MODE OF COLLAPSE OF SQUARE SINGLE PANEL REINFORCED CONCRETE SPACE- FRAMED STRUCTURES.... L. M. Olantori, et al. Nigerian Journal of Technology. Vol. 35, No. 1, January 2016. 17 particularly in exterior joints where additional sources of shear transfer within the joint region cannot develop after first ...

  17. Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard

    Science.gov (United States)

    Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.

    2016-12-01

    Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers

  18. Probing the accretion induced collapse of white dwarfs in millisecond pulsars

    Science.gov (United States)

    Taani, A.; Khasawneh, A.

    2017-06-01

    This paper investigates the progenitors of Millisecond Pulsars (MSPs) with a distribution of long orbital periods (Porb > 2 d), to show the link between white dwarf (WD) binaries and long orbits for some binary MSPs through the Accretion Induced Collapse (AIC) of a WD. For this purpose, a model is presented to turn binary MSPs into wide binaries and highly circular orbits (e pulsar during the AIC process, which may indicate a sizeable kick velocity along the rotation of the proto-neutron star. The results show the effects of shock wave, binding energy, and mass loss (0.2M⊙). The model shows the pulsar systems are relevant to AIC-candidates.

  19. Globular Cluster formation in a collapsing supershell

    Science.gov (United States)

    Recchi, S.; Wünsch, R.; Palouš, J.; Dinnbier, F.

    2017-10-01

    Primordial clouds are supposed to host the so-called population III stars. These stars are very massive and completely metal-free. The final stage of the life of population III stars with masses between 130 and 260 solar masses is a very energetic hypernova explosion. A hypernova drives a shock, behind which a spherically symmetric very dense supershell forms, which might become gravitationally unstable, fragment, and form stars. In this paper we study under what conditions can an expanding supershell become gravitationally unstable and how the feedback of these supershell stars (SSSs) affects its surroundings. We simulate, by means of a 1-D Eulerian hydrocode, the early evolution of the primordial cloud after the hypernova explosion, the formation of SSSs, and the following evolution, once the SSSs start to release energy and heavy elements into the interstellar medium. Our results indicate that a shell, enriched with nucleosynthetic products from SSSs, propagates inwards, towards the center of the primordial cloud. In a time span of a few Myr, this inward-propagating shell reaches a distance of only a few parsec away from the center of the primordial cloud. Its density is extremely high and its temperature very low, thus the conditions for a new episode of star formation are achieved. We study what fraction of these two distinct populations of stars can remain bound and survive until the present day. We study also under what conditions can this process repeat and form multiple stellar populations. We extensively discuss whether the proposed scenario can help to explain some open questions of the formation mechanism of globular clusters.

  20. Architecture of collapse: regime shift and recovery in an hierarchically structured marine ecosystem.

    Science.gov (United States)

    Daskalov, Georgi M; Boicenco, Laura; Grishin, Alexandre N; Lazar, Luminita; Mihneva, Vesselina; Shlyakhov, Vladislav A; Zengin, Mustafa

    2017-04-01

    By the late 20th century, a series of events or 'natural experiments', for example the depletion of apex predators, extreme eutrophication and blooms of invasive species, had suggested that the Black Sea could be considered as a large ecosystem 'laboratory'. The events resulted in regime shifts cascading through all trophic levels, disturbing ecosystem functioning and damaging the water environment. Causal pathways by which the external (hydroclimate, overfishing) and internal (food web interactions) drivers provoke regime shifts are investigated. Statistical data analyses supported by an interpretative framework based on hierarchical ecosystem theory revealed mechanisms of hierarchical incorporation of environmental factors into the ecosystem. Evidence links Atlantic teleconnections to Black Sea hydroclimate, which together with fishing shapes variability in fish stocks. The hydroclimatic signal is conveyed through the food web via changes in productivity at all levels, to planktivorous fish. Fluctuating fish abundance is believed to induce a lagged change in competitor jelly plankton that cascades down to phytoplankton and influences water quality. Deprived of the stabilising role of apex predators, the Black Sea's hierarchical ecosystem organisation is susceptible to both environmental and anthropogenic stresses, and increased fishing makes fish stock collapses highly probable. When declining stocks are confronted with burgeoning fishing effort associated with the inability of fishery managers and decision-makers to adapt rapidly to changes in fish abundance, there is overfishing and stock collapse. Management procedures are ineffective at handling complex phenomena such as ecosystem regime shifts because of the shortage of suitable explanatory models. The proposed concepts and models reported here relate the hydroclimate, overfishing and invasive species to shifts in ecosystem functioning and water quality, unravelling issues such as the causality of ecosystem

  1. Solar Indices

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection includes a variety of indices related to solar activity contributed by a number of national and private solar observatories located worldwide. This...

  2. RBC indices

    Science.gov (United States)

    ... this. The results are used to diagnose different types of anemia . ... These test results indicate the type of anemia: MCV below normal. Microcytic anemia (may be due to low iron levels, lead poisoning, or thalassemia ). MCV normal. Normocytic anemia (may ...

  3. Dynamics of the Presence of Israeli Acute Paralysis Virus in Honey Bee Colonies with Colony Collapse Disorder

    Directory of Open Access Journals (Sweden)

    Chunsheng Hou

    2014-05-01

    Full Text Available The determinants of Colony Collapse Disorder (CCD, a particular case of collapse of honey bee colonies, are still unresolved. Viruses including the Israeli acute paralysis virus (IAPV were associated with CCD. We found an apiary with colonies showing typical CCD characteristics that bore high loads of IAPV, recovered some colonies from collapse and tested the hypothesis if IAPV was actively replicating in them and infectious to healthy bees. We found that IAPV was the dominant pathogen and it replicated actively in the colonies: viral titers decreased from April to September and increased from September to December. IAPV extracted from infected bees was highly infectious to healthy pupae: they showed several-fold amplification of the viral genome and synthesis of the virion protein VP3. The health of recovered colonies was seriously compromised. Interestingly, a rise of IAPV genomic copies in two colonies coincided with their subsequent collapse. Our results do not imply IAPV as the cause of CCD but indicate that once acquired and induced to replication it acts as an infectious factor that affects the health of the colonies and may determine their survival. This is the first follow up outside the US of CCD-colonies bearing IAPV under natural conditions.

  4. Dynamics of the Presence of Israeli Acute Paralysis Virus in Honey Bee Colonies with Colony Collapse Disorder

    Science.gov (United States)

    Hou, Chunsheng; Rivkin, Hadassah; Slabezki, Yossi; Chejanovsky, Nor

    2014-01-01

    The determinants of Colony Collapse Disorder (CCD), a particular case of collapse of honey bee colonies, are still unresolved. Viruses including the Israeli acute paralysis virus (IAPV) were associated with CCD. We found an apiary with colonies showing typical CCD characteristics that bore high loads of IAPV, recovered some colonies from collapse and tested the hypothesis if IAPV was actively replicating in them and infectious to healthy bees. We found that IAPV was the dominant pathogen and it replicated actively in the colonies: viral titers decreased from April to September and increased from September to December. IAPV extracted from infected bees was highly infectious to healthy pupae: they showed several-fold amplification of the viral genome and synthesis of the virion protein VP3. The health of recovered colonies was seriously compromised. Interestingly, a rise of IAPV genomic copies in two colonies coincided with their subsequent collapse. Our results do not imply IAPV as the cause of CCD but indicate that once acquired and induced to replication it acts as an infectious factor that affects the health of the colonies and may determine their survival. This is the first follow up outside the US of CCD-colonies bearing IAPV under natural conditions. PMID:24800677

  5. Geographical Indications

    OpenAIRE

    Anechitoae Constantin; Grigoru? Lavinia-Maria

    2011-01-01

    “The denomination of origin” may be the name of a region, a specific place or country used to describe an agricultural or food product. "The geographical indication" may be the name of a region, a specific place or a country, used to describe an agricultural or food product. The indication of provenance and the denomination of origin serve to identify the source and origin of goods or services.

  6. Is an Apicomplexan Parasite Responsible for the Collapse of the Iceland Scallop (Chlamys islandica) Stock?

    Science.gov (United States)

    Kristmundsson, Árni; Erlingsdóttir, Ásthildur; Freeman, Mark A

    2015-01-01

    Due to the total and unexpected collapse of the Iceland scallop, Chlamys islandica, stocks around Iceland during the 2000s, a commercial fishing ban has been imposed on this valuable resource since 2003. Following the initial identification of an apicomplexan parasite in the scallops, a long-term surveillance program was established to evaluate the effect of the parasite on the population. The infections were highly prevalent in all shell sizes throughout the study. However, the parasite only impacts mature scallops where they cause severe macroscopic changes, characterized by an extensively diminished and abnormally coloured adductor muscle. A highly significant relationship was observed between infection intensity and gonad and adductor muscle indices. The first four years of the study, were characterized by high infection intensity and very poor condition of the adductor muscle and gonads, whilst during subsequent years, infections gradually decreased and the condition of the scallops improved. Histopathological changes were restricted to the presence of apicomplexan zoites which were widely distributed, causing varying degrees of pathology in all organs. In heavy infections, muscular and connective tissues were totally necrotized, destroying significant parts of numerous organs, especially the adductor muscle, digestive gland and gonads. The progression of the disease was in good synchrony with the mortality rates and the subsequent decline observed in the scallop stock and recruitment indices. Our findings strongly suggest that the apicomplexan parasite played a major role in the collapse of the Iceland scallop stock in Breidafjordur. In addition to causing mortality, the infections significantly impact gonad development which contributes further to the collapse of the stock in the form of lower larval recruitment. Furthermore, compelling evidence exists that this apicomplexan pathogen is causing serious disease outbreaks in other scallop populations. Similar

  7. Distinct Element modeling of geophysical signatures during sinkhole collapse

    Science.gov (United States)

    Al-Halbouni, Djamil; Holohan, Eoghan P.; Taheri, Abbas; Dahm, Torsten

    2017-04-01

    A sinkhole forms due to the collapse of rocks or soil near the Earth's surface into an underground cavity. Such cavities represent large secondary pore spaces derived by dissolution and subrosion in the underground. By changing the stress field in the surrounding material, the growth of cavities can lead to a positive feedback, in which expansion and mechanical instability in the surrounding material increases or generates new secondary pore space (e.g. by fracturing), which in turn increases the cavity size, etc. A sinkhole forms due to the eventual subsidence or collapse of the overburden that becomes destabilized and fails all the way to the Earth's surface. Both natural processes like (sub)surface water movement and earthquakes, and human activities, such as mining, construction and groundwater extraction, intensify such feedbacks. The development of models for the mechanical interaction of a growing cavity and fracturing of its surrounding material, thus capturing related precursory geophysical signatures, has been limited, however. Here we report on the advances of a general, simplified approach to simulating cavity growth and sinkhole formation by using 2D Distinct Element Modeling (DEM) PFC5.0 software and thereby constraining pre-, syn- and post-collapse geophysical and geodetic signatures. This physically realistic approach allows for spontaneous cavity development and dislocation of rock mass to be simulated by bonded particle formulation of DEM. First, we present calibration and validation of our model. Surface subsidence above an instantaneously excavated circular cavity is tracked and compared with an incrementally increasing dissolution zone both for purely elastic and non-elastic material.This validation is important for the optimal choice of model dimensions and particles size with respect to simulation time. Second, a cavity growth approach is presented and compared to a well-documented case study, the deliberately intensified sinkhole collapse at

  8. Experimental study of the progressive collapse mechanism of excavations retained by cantilever piles

    National Research Council Canada - National Science Library

    Diao, Y; Nie, D.Q; Deng, C.H; Zheng, G; Cheng, X.S; Huang, T.M; Lei, Y.W

    2017-01-01

    ... (sudden failures of certain retaining piles) and progressive collapse. The model test results show that partial collapse can cause a sudden increase in the bending moments of adjacent piles via an arching effect...

  9. Alcohol increases hypnotic susceptibility.

    Science.gov (United States)

    Semmens-Wheeler, Rebecca; Dienes, Zoltán; Duka, Theodora

    2013-09-01

    One approach to hypnosis suggests that for hypnotic experience to occur frontal lobe activity must be attenuated. For example, cold control theory posits that a lack of awareness of intentions is responsible for the experience of involuntariness and/or the subjective reality of hypnotic suggestions. The mid-dorso-lateral prefrontal cortex and the ACC are candidate regions for such awareness. Alcohol impairs frontal lobe executive function. This study examined whether alcohol affects hypnotisability. We administered 0.8 mg/kg of alcohol or a placebo to 32 medium susceptible participants. They were subsequently hypnotised and given hypnotic suggestions. All participants believed they had received some alcohol. Participants in the alcohol condition were more susceptible to hypnotic suggestions than participants in the placebo condition. Impaired frontal lobe activity facilitates hypnotic responding, which supports theories postulating that attenuation of executive function facilitates hypnotic response, and contradicts theories postulating that hypnotic response involves enhanced inhibitory, attentional or other executive function. Copyright © 2013. Published by Elsevier Inc.

  10. Position indicator

    Science.gov (United States)

    Tanner, David E.

    1981-01-01

    A nuclear reactor system is described in which a position indicator is provided for detecting and indicating the position of a movable element inside a pressure vessel. The movable element may be a valve element or similar device which moves about an axis. Light from a light source is transmitted from a source outside the pressure vessel to a first region inside the pressure vessel in alignment with the axis of the movable element. The light is redirected by a reflector prism to a second region displaced radially from the first region. The reflector prism moves in response to movement of the movable element about its axis such that the second region moves arcuately with respect to the first region. Sensors are arrayed in an arc corresponding to the arc of movement of the second region and signals are transmitted from the sensors to the exterior of the reactor vessel to provide indication of the position of the movable element.

  11. Susceptibility of pathogenic and nonpathogenic Naegleria ssp

    Energy Technology Data Exchange (ETDEWEB)

    Whiteman, L.Y.

    1988-01-01

    The susceptibility of four species of Naegleria amoebae to complement-mediated lysis was determined. The amoebicidal activity of normal human serum (NHS) and normal guinea pig serum (NGPS) for Naegleria amoebae was measured by an in vitro cytotoxicity assay. Release of radioactivity from amoebae labeled with {sup 3}H-uridine and visual observation with a compound microscope were used as indices of lysis. Susceptibility or resistance to complement-mediated lysis in vitro correlated with the in vivo pathogenic potential. Nonpathogenic Naegleria amoebae were lysed at a faster rate and at higher cell concentrations than were pathogenic amoebae. Electrophoretic analysis of NHS incubated with pathogenic or nonpathogenic Naegleria spp. demonstrated that amoebae activate the complement cascade resulting in the production of C3 and C5 complement cleavage products. Treatment with papain or trypsin for 1 h, but not with sialidase, increase the susceptibility of highly pathogenic, mouse-passaged N. fowleri to lysis. Treatment with actinomycin D, cycloheximide or various protease inhibitors for 4 h did not increase susceptibility to lysis. Neither a repair process involving de novo protein synthesis nor a complement-inactivating protease appear to account for the increase resistance of N. fowleri amoebae to complement-mediated lysis. A binding study with {sup 125}I radiolabeled C9 indicated that the terminal complement component does not remain stably bound to the membrane of pathogenic amoebae.

  12. yield indicators

    African Journals Online (AJOL)

    YIELD INDICATORS. P. NTAWURUHUNGA, P.R. RUBAIHAYOI, J.B.A. WHYTE, A.G.O. DIXONZ and use. osnzu1. International Institute of Tropical Agriculture, East and Southern Africa, Centre, PO. Box 7878, l Kampala ... most important sources of food energy in several ... efficiency in selecting and identifying cassava.

  13. Anthropometric indices

    DEFF Research Database (Denmark)

    Oguoma, V. M.; Nwose, E. U.; Skinner, T. C.

    2016-01-01

    BACKGROUND: The current anthropometric indices used for diagnosis of cardio-metabolic syndrome (CMS) in sub-Saharan Africa are those widely validated in the western world. We hereby aim to compare the sensitivity and specificity of these tools in identifying risk factors for CMS. METHOD: The study...

  14. Electron-ion thermal equilibration after spherical shock collapse

    Energy Technology Data Exchange (ETDEWEB)

    Rygg, J R; Frenje, J A; Li, C K; Seguin, F H; Petrasso, R D; Meyerhofer, D D; Stoeckl, C

    2009-08-14

    A comprehensive set of dual nuclear product observations provides a snapshot of imploding inertial confinement fusion capsules at the time of shock collapse, shortly before the final stages of compression. The collapse of strong convergent shocks at the center of spherical capsules filled with D{sub 2} and {sup 3}He gas induces D-D and D-{sup 3}He nuclear production. Temporal and spectral diagnostics of products from both reactions are used to measure shock timing, temperature, and capsule areal density. The density and temperature inferred from these measurements are used to estimate the electron-ion thermal coupling, and demonstrate a lower electron-ion relaxation rate for capsules with lower initial gas density.

  15. Quantum gravitational collapse: non-singularity and non-locality

    Science.gov (United States)

    Greenwood, Eric; Stojkovic, Dejan

    2008-06-01

    We investigate gravitational collapse in the context of quantum mechanics. We take primary interest in the behavior of the collapse near the horizon and near the origin (classical singularity) from the point of view of an infalling observer. In the absence of radiation, quantum effects near the horizon do not change the classical conclusions for an infalling observer, meaning the horizon is not an obstacle for him. However, quantum effects are able to remove the classical singularity at the origin, since the wave function is non-singular at the origin. Also, near the classical singularity, some non-local effects become important. In the Schrodinger equation describing behavior near the origin, derivatives of the wave function at one point are related to the value of the wave function at some other distant point.

  16. Radiation from a Collapsing Object is Manifestly Unitary

    Science.gov (United States)

    Saini, Anshul; Stojkovic, Dejan

    2015-03-01

    The process of gravitational collapse excites the fields propagating in the background geometry and gives rise to thermal radiation. We demonstrate by explicit calculations that the density matrix corresponding to such radiation actually describes a pure state. While Hawking's leading order density matrix contains only the diagonal terms, we calculate the off-diagonal correlation terms. These correlations start very small, but then grow in time. The cumulative effect is that the correlations become comparable to the leading order terms and significantly modify the density matrix. While the trace of the Hawking's density matrix squared goes from unity to zero during the evolution, the trace of the total density matrix squared remains unity at all times and all frequencies. This implies that the process of radiation from a collapsing object is unitary.

  17. Classes of Copenhagen interpretations: Mechanisms of collapse as typologically determinative

    Science.gov (United States)

    Henderson, James R.

    The Copenhagen interpretation of quantum mechanics is the dominant view of the theory among working physicists, if not philosophers. There are, however, several strains of Copenhagenism extant, each largely accepting Born's assessment of the wave function as the most complete possible specification of a system and the notion of collapse as a completely random event. This paper outlines three of these sub-interpretations, typing them by what the author of each names as the trigger of quantum-mechanical collapse. Visions of the theory from von Neumann, Heisenberg, and Wheeler offer different mechanisms to break the continuous, deterministic, superposition-laden quantum chain and yield discrete, probabilistic, classical results in response to von Neumann's catastrophe of infinite regress.

  18. Cellular membrane collapse by atmospheric-pressure plasma jet

    Science.gov (United States)

    Kim, Kangil; Jun Ahn, Hak; Lee, Jae-Hyeok; Kim, Jae-Ho; Sik Yang, Sang; Lee, Jong-Soo

    2014-01-01

    Cellular membrane dysfunction caused by air plasma in cancer cells has been studied to exploit atmospheric-pressure plasma jets for cancer therapy. Here, we report that plasma jet treatment of cervical cancer HeLa cells increased electrical conductivity across the cellular lipid membrane and caused simultaneous lipid oxidation and cellular membrane collapse. We made this finding by employing a self-manufactured microelectrode chip. Furthermore, increased roughness of the cellular lipid membrane and sequential collapse of the membrane were observed by atomic force microscopy following plasma jet treatment. These results suggest that the cellular membrane catastrophe occurs via coincident altered electrical conductivity, lipid oxidation, and membrane roughening caused by an atmospheric-pressure plasma jet, possibly resulting in cellular vulnerability to reactive species generated from the plasma as well as cytotoxicity to cancer cells.

  19. Neutrinos and nucleosynthesis in core-collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Fröhlich, C.; Casanova, J. [Department of Physics, North Carolina State University, Raleigh, NC, 27695 (United States); Hempel, M.; Liebendörfer, M. [Departement für Physik, Universität Basel, CH-4056 Basel (Switzerland); Melton, C. A. [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Perego, A. [Institut für Kernphysik, Technische Universität Darmstadt, D-64289 Darmstadt (Germany)

    2014-01-01

    Massive stars (M > 8-10 M{sub ⊙}) undergo core collapse at the end of their life and explode as supernova with ~ 10⁵¹ erg of kinetic energy. While the detailed supernova explosion mechanism is still under investigation, reliable nucleosynthesis calculations based on successful explosions are needed to explain the observed abundances in metal-poor stars and to predict supernova yields for galactic chemical evolution studies. To predict nucleosynthesis yields for a large number of progenitor stars, computationally efficient explosion models are required. We model the core collapse, bounce and subsequent explosion of massive stars assuming spherical symmetry and using detailed microphysics and neutrino physics combined with a novel method to artificially trigger the explosion (PUSH). We discuss the role of neutrinos, the conditions in the ejecta, and the resulting nucleosynthesis.

  20. Gravitational perfect fluid collapse in Gauss-Bonnet gravity

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, G.; Tahir, M. [The Islamia University of Bahawalpur, Department of Mathematics, Bahawalpur (Pakistan)

    2017-08-15

    The Einstein Gauss-Bonnet theory of gravity is the low-energy limit of heterotic super-symmetric string theory. This paper deals with gravitational collapse of a perfect fluid in Einstein-Gauss-Bonnet gravity by considering the Lemaitre-Tolman-Bondi metric. For this purpose, the closed form of the exact solution of the equations of motion has been determined by using the conservation of the stress-energy tensor and the condition of marginally bound shells. It has been investigated that the presence of a Gauss-Bonnet coupling term α > 0 and the pressure of the fluid modifies the structure and time formation of singularity. In this analysis a singularity forms earlier than a horizon, so the end state of the collapse is a naked singularity depending on the initial data. But this singularity is weak and timelike, which goes against the investigation of general relativity. (orig.)

  1. Short intense laser pulse collapse in near-critical plasma.

    Science.gov (United States)

    Sylla, F; Flacco, A; Kahaly, S; Veltcheva, M; Lifschitz, A; Malka, V; d'Humières, E; Andriyash, I; Tikhonchuk, V

    2013-02-22

    It is observed that the interaction of an intense ultrashort laser pulse with a near-critical gas jet results in the pulse collapse and the deposition of a significant fraction of the energy. This deposition happens in a small and well-localized volume in the rising part of the gas jet, where the electrons are efficiently accelerated and heated. A collisionless plasma expansion over ~ 150 μm at a subrelativistic velocity (~ c/3) has been optically monitored in time and space, and attributed to the quasistatic field ionization of the gas associated with the hot electron current. Numerical simulations in good agreement with the observations suggest the acceleration in the collapse region of relativistic electrons, along with the excitation of a sizable magnetic dipole that sustains the electron current over several picoseconds.

  2. Sterile neutrino oscillations in core-collapse supernovae

    Science.gov (United States)

    Warren, MacKenzie L.; Meixner, Matthew; Mathews, Grant; Hidaka, Jun; Kajino, Toshitaka

    2014-11-01

    We have made core-collapse supernova simulations that allow oscillations between electron neutrinos (or their antiparticles) with right-handed sterile neutrinos. We have considered a range of mixing angles and sterile neutrino masses including those consistent with sterile neutrinos as a dark matter candidate. We examine whether such oscillations can impact the core bounce and shock reheating in supernovae. We identify the optimum ranges of mixing angles and masses that can dramatically enhance the supernova explosion by efficiently transporting electron antineutrinos from the core to behind the shock, where they provide additional heating leading to much larger explosion kinetic energies. We show that this effect can cause stars to explode that otherwise would have collapsed. We find that an interesting periodicity in the neutrino luminosity develops due to a cycle of depletion of the neutrino density by conversion to sterile neutrinos that shuts off the conversion, followed by a replenished neutrino density as neutrinos transport through the core.

  3. Quantum Mechanical Stabilization of a Collapsing Bose-Bose Mixture.

    Science.gov (United States)

    Petrov, D S

    2015-10-09

    According to the mean-field theory a condensed Bose-Bose mixture collapses when the interspecies attraction becomes stronger than the geometrical average of the intraspecies repulsions, g_{12}^{2}>g_{11}g_{22}. We show that instead of collapsing such a mixture gets into a dilute liquidlike droplet state stabilized by quantum fluctuations thus providing a direct manifestation of beyond mean-field effects. We study various properties of the droplet and find, in particular, that in a wide range of parameters its excitation spectrum lies entirely above the particle emission threshold. The droplet thus automatically evaporates itself to zero temperature, the property potentially interesting by itself and from the viewpoint of sympathetic cooling of other systems.

  4. Suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by As75 NMR/NQR measurements

    Science.gov (United States)

    Furukawa, Y.; Roy, B.; Ran, S.; Bud'ko, S. L.; Canfield, P. C.

    2014-03-01

    The static and the dynamic spin correlations in the low-temperature collapsed tetragonal and the high-temperature tetragonal phase in CaFe2As2 have been investigated by As75 nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements. Through the temperature (T) dependence of the nuclear spin lattice relaxation rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic (AFM) spin correlations are realized in the high-temperature tetragonal phase, no trace of the AFM spin correlations can be found in the nonsuperconducting, low-temperature, collapsed tetragonal (cT) phase. Given that there is no magnetic broadening in As75 NMR spectra, together with the T-independent behavior of magnetic susceptibility χ and the T dependence of 1/T1Tχ, we conclude that Fe spin correlations are completely quenched statically and dynamically in the nonsuperconducting cT phase in CaFe2As2.

  5. Role of primordial black holes in the direct collapse scenario of ...

    Indian Academy of Sciences (India)

    In this paper, we explore the possibility of accreting primordial black holes as the source of heating for the collapsing gas in the context of the direct collapse black hole scenario for the formation of super-massive black holes (SMBHs) at high redshifts, z ∼ 6 – 7 . One of the essential requirements for the direct collapse model ...

  6. Collapse arresting in an inhomogeneous two-dimensional nonlinear Schrodinger model

    DEFF Research Database (Denmark)

    Schjødt-Eriksen, Jens; Gaididei, Yuri Borisovich; Christiansen, Peter Leth

    2001-01-01

    Collapse of (2 + 1)-dimensional beams in the inhomogeneous two-dimensional cubic nonlinear Schrodinger equation is analyzed numerically and analytically. It is shown that in the vicinity of a narrow attractive inhomogeneity, the collapse of beams that in a homogeneous medium would collapse may be...

  7. Non-adiabatic radiative collapse of a relativistic star under different ...

    Indian Academy of Sciences (India)

    used this space-time metric and examined various features of the evolution of the collapse of a shear-free homogeneous and isotropic configuration of matter. Pinheiro and Chan. [4,5] analysed the collapse of a matter distribution of uniform matter density with shear. We have examined the collapse of a relativistic star with ...

  8. Asymmetries in core-collapse supernovae from maps of radioactive 44Ti in Cassiopeia A

    DEFF Research Database (Denmark)

    Grefenstette, B W; Harrison, F A; Boggs, S E

    2014-01-01

    Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive (44)Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing......, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae....

  9. Solar flare particle acceleration in collapsing magnetic traps

    OpenAIRE

    Grady, Keith J.

    2012-01-01

    The topic of this thesis is a detailed investigation of different aspects of the particle acceleration mechanisms operating in Collapsing Magnetic Traps (CMTs), which have been suggested as one possible mechanism for particle acceleration during solar flares. The acceleration processes in CMTs are investigated using guiding centre test particle calculations. Results including terms of different orders in the guiding centre approximation are compared to help identify which of the terms a...

  10. Observing Atomic Collapse Resonances in Artificial Nuclei on Graphene

    Science.gov (United States)

    2013-03-07

    Recent- ly subcritical Coulomb behavior (i.e., where Z < Zc and atomic collapse resonances are absent) was observed for charged impurities in graphene...impurities. Here we report the observation of supercritical Coulomb behavior in atomically-fabricated “artificial nuclei” assembled on the surface...an STM, thus al- lowing creation of supercritical Coulomb potentials from subcritical charge elements. STM spectroscopy was used to observe the

  11. Results of Integrated Investigation of Collapse Sinkhole in Sarkayevo Village

    OpenAIRE

    O. N. Kovin; S. M. Blinov; P. A. Belkin; S. S. Vaganov; Bhavik Lodhia; Ruth Amey; Gan Yuqian

    2014-01-01

    The integrated investigations of karstic collapse sinkhole were conducted at the area of Sarkayevo village. The obtained hydrogeologic data show the local concentration of underground water flow at the investigated site, and high sulfate ion content in the water samples that suggests that a sinkhole is karstic in nature. Geophysical investigations allowed determining basic parameters of the site geological structure, to reveal the depth distribution of the disturbed ground in vicinity of the ...

  12. Collapse, conquest and Maya survival at Lamanai, Belize

    Directory of Open Access Journals (Sweden)

    Elizabeth Graham

    2000-11-01

    Full Text Available The Maya civilization of Central America prompts visions of mysterious stone temples now buried in tropical forest. It is commonly supposed to have collapsed suddenly in the ninth century AD, but some Maya settlements, such as Lamanai, survived into the colonial period. Here a new member of the Institute's academic staff gives a personal account of how working in Belize transformed her understanding of Maya civilization and its aftermath.

  13. The interest in neutrinos from core collapse supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Costantini, M.L. [Universita dell' Aquila, I-67010 (Italy); Ianni, A. [Universita dell' Aquila, I-67010 (Italy); Vissani, F. [INFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi (AQ) (Italy)

    2005-02-15

    The understanding of core collapse supernovae (SN) is an important open problem. These objects are intense sources of neutrinos, that can be observed with several types of terrestrial detectors. These two simple considerations, already, motivate close attention toward neutrino interactions in the region from few to 200 MeV. In this work, we offer a selection of results and expectations, and discuss important goals still to be reached.

  14. Thermal collapse of a granular gas under gravity

    OpenAIRE

    Volfson, Dmitri; Meerson, Baruch; Tsimring, Lev S.

    2006-01-01

    Free cooling of a gas of inelastically colliding hard spheres represents a central paradigm of kinetic theory of granular gases. At zero gravity the temperature of a freely cooling homogeneous granular gas follows a power law in time. How does gravity, which brings inhomogeneity, affect the cooling? We combine molecular dynamics simulations, a numerical solution of hydrodynamic equations and an analytic theory to show that a granular gas cooling under gravity undergoes thermal collapse: it co...

  15. Some nuclear physics aspects of core-collapse supernovae

    OpenAIRE

    Qian, Yong-Zhong

    1998-01-01

    Here I review some nuclear physics aspects of core-collapse supernovae concerning neutrinos. Studies of neutrino emission and interactions in supernovae are crucial to our understanding of the explosion mechanism, the heavy element nucleosynthesis, and pulsar proper motions. I discuss the effects of reduced neutrino opacities in dense nuclear matter on supernova neutrino emission and their implications for the delayed supernova explosion mechanism and the synthesis of neutron-rich heavy eleme...

  16. A model for voltage collapse study considering load characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, L.B. [Companhia de Energia Eletrica da Bahia (COELBA), Salvador, BA (Brazil)

    1994-12-31

    This paper presents a model for analysis of voltage collapse and instability problem considering the load characteristics. The model considers fundamentally the transmission lines represented by exact from through the generalized constants A, B, C, D and the loads as function of the voltage, emphasizing the cases of constant power, constant current and constant impedance. the study treats of the system behavior on steady state and presents illustrative graphics about the problem. (author) 12 refs., 4 figs.

  17. Collapsing Focal Segmental Glomerulosclerosis in a Patient with Acute Malaria

    Directory of Open Access Journals (Sweden)

    Najamus Sehar

    2015-01-01

    seen in association with HIV infection. Rare data is available about the association between collapsing FSGS and malaria. Case Description. A 72-year-old African male patient presented to the hospital for generalized body aches, fatigue, fever, and night sweats for three days. He had history of recent travel to Ghana. Patient looked in acute distress and was shivering. Laboratory tests showed elevated serum creatinine (Cr of 2.09 mg/dL (baseline was 1.5 mg/dL in 2012. Hospital course was significant for rapid elevation of Cr to 9.5 mg/dL and proteinuria of 7.9 grams. Autoimmune studies resulted negative. Blood smear resulted positive for Plasmodium falciparum and patient was treated with Artemether/Lumefantrine. Patient’s fever and pain improved, but kidney function continued to deteriorate and he became oliguric. On day seven, he was started on Hemodialysis. Tests for different causes of glomerular pathology were also negative. He underwent left kidney biopsy which resulted in findings consistent with severe collapsing glomerulopathy. Discussion. This case illustrates a biopsy proven collapsing FSGS likely secondary to malarial infection requiring renal replacement therapy. Literature review revealed only few case reports that suggested the possible association of malaria with secondary form of FSGS.

  18. Bounds on collapse models from cold-atom experiments

    Science.gov (United States)

    Bilardello, Marco; Donadi, Sandro; Vinante, Andrea; Bassi, Angelo

    2016-11-01

    The spontaneous localization mechanism of collapse models induces a Brownian motion in all physical systems. This effect is very weak, but experimental progress in creating ultracold atomic systems can be used to detect it. In this paper, we considered a recent experiment (Kovachy et al., 2015), where an atomic ensemble was cooled down to picokelvins. Any Brownian motion induces an extra increase of the position variance of the gas. We study this effect by solving the dynamical equations for the Continuous Spontaneous Localizations (CSL) model, as well as for its non-Markovian and dissipative extensions. The resulting bounds, with a 95 % of confidence level, are beaten only by measurements of spontaneous X-ray emission and by experiments with cantilever (in the latter case, only for rC ≥ 10-7 m, where rC is one of the two collapse parameters of the CSL model). We show that, contrary to the bounds given by X-ray measurements, non-Markovian effects do not change the bounds, for any reasonable choice of a frequency cutoff in the spectrum of the collapse noise. Therefore the bounds here considered are more robust. We also show that dissipative effects are unimportant for a large spectrum of temperatures of the noise, while for low temperatures the excluded region in the parameter space is the more reduced, the lower the temperature.

  19. Collapsed fat navigators for brain 3D rigid body motion.

    Science.gov (United States)

    Engström, Mathias; Mårtensson, Magnus; Avventi, Enrico; Norbeck, Ola; Skare, Stefan

    2015-10-01

    To acquire high-resolution 3D multi-slab echo planar imaging data without motion artifacts, using collapsed fat navigators. A fat navigator module (collapsed FatNav) was added to a diffusion-weighted 3D multi-slab echo planar imaging (DW 3D-MS EPI) sequence, comprising three orthogonal echo planar imaging readouts to track rigid body head motion in the image domain and performing prospective motion correction. The stability, resolution and accuracy of the navigator were investigated on phantoms and healthy volunteers. The experiments on phantoms and volunteers show that the navigator, depicting projections of the subcutaneous fat in of the head, is capable of correcting for head motion with insignificant bias compared to motion estimates derived from the water-signaling DWI images. Despite that this projection technique implies a non-sparse image appearance, collapsed FatNav data could be highly accelerated with parallel imaging, allowing three orthogonal 2D EPI readouts in about 6ms. By utilizing signal from the leading fat saturation RF pulse of the diffusion sequence, only the readout portion of the navigator needs to be added, resulting in a scan time penalty of only about 5%. Motion can be detected and corrected for with a 5-10Hz update frequency when combined with a sequence like the DW 3D-MS EPI. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Hospital response to a major freeway bridge collapse.

    Science.gov (United States)

    Hick, John L; Chipman, Jeffery; Loppnow, Gregory; Conterato, Marc; Roberts, David; Heegaard, William G; Beilman, Greg; Clark, Michael; Pohland, Jonathan; Ho, Jeffrey D; Brunette, Douglas D; Clinton, Joseph E

    2008-09-01

    We describe the hospital system response to the Interstate 35W bridge collapse in Minneapolis into the Mississippi River on August 1, 2007, which resulted in 13 deaths and 127 injuries. Comparative analysis of response activities at the 3 hospitals that received critical or serious casualties is provided. First-hand experiences of hospital physicians, issues identified in after-action reports, injury severity scores, and other relevant patient data were collected from the 3 hospitals that received seriously injured patients, including the closest hospitals to the collapse on each side of the river. Injuries were consistent with major acceleration/deceleration force injuries. The most critical patients arrived first at each hospital, suggesting appropriate prehospital triage. Capacity of the health care system was not overwhelmed and the involved hospitals generally reported an overresponse by staff. Communication and patient tracking problems occurred at all of the hospitals. Situational awareness was limited due to the scope of structural collapse and incomplete information from the scene. Hospitals were generally satisfied with their surge capacity and incident management plan activation. Issues such as communications, patient tracking, and staff overreporting that have been identified in past incidents also were problematic in this event. Hospitals will need to address deficiencies and build on successful actions to cope with future, potentially larger incidents.

  1. Plastic Collapse Localisation in Simple Shearing and Coaxial Deformations

    Science.gov (United States)

    Hobbs, B. E.; Ord, A.

    2011-12-01

    We explore, numerically, the evolution of localisation due to plastic collapse in both coaxial shortening and simple shearing deformations. These localisation features arise from plastic behaviour and hence differ from the formation of anticracks modelled by linear elastic behaviour (Fletcher and Pollard, 1990). The behaviour is close to that discussed by Rudnicki (2004) and Chemenda (2009) in that localisation consists of zones of plastic collapse separated by elastically unloaded regions. The constitutive behaviour assumed here comprises a Tresca yield with both strain-softening of the yield stress and of a cap that models plastic volumetric collapse during phase transformations, such as the olivine-spinel transition, with ΔVSudbury, Ontario, Canada, October 2003. R. Brummer (Ed), Balkema, 27-33. Fletcher, R.C., Pollard, D.D., 1990. Anticrack model for pressure solution surfaces. Geology 9, 419- 424. Green, H.W., Burnley, P.C., 1989. A new self-organizing mechanism for deep-focus earthquakes. Nature, 341, 733- 737. Issen, K.A., Rudnicki, J.W., 2000. Conditions for compaction bands in porous rocks. J. Geophys. Res. 105, 21,529-21,536. Rudnicki, J. W. 2004. Shear and compaction band formation on an elliptic yield cap. J. Geophys. Res., 109, B03402. Veveakis, E., Alevizos, S., & Vardoulakis, I. 2010. Chemical reaction capping of thermal instabilities during shear of frictional faults. Journal of the Mechanics and Physics of Solids. 58, 1175-1194.

  2. Cardiovascular collapse in infants: association with paroxysmal atrial tachycardia.

    Science.gov (United States)

    Gikonyo, B M; Dunnigan, A; Benson, D W

    1985-12-01

    Four infants, aged 16 to 28 days (mean 23 days), were seen in the emergency room with acute cardiovascular collapse and with normal heart rate and rhythm. During evaluation for cardiovascular collapse, no infant had sepsis; cardiac assessment revealed normal intracardiac anatomy but global cardiac chamber enlargement and poor left ventricular systolic function, which resolved with supportive treatment. However, three of the four infants demonstrated ventricular preexcitation on their surface electrocardiogram and, subsequently, two infants had transient episodes of tachycardia. During a transesophageal pacing study to evaluate inducibility and electrophysiologic characteristics of tachycardia, sustained tachycardia was initiated in all four infants. Reentrant tachycardia used an accessory atrioventricular connection as evidenced by the presence of preexcitation during sinus rhythm (three infants), the ability to initiate and terminate tachycardia by programmed electrical stimulation (four infants), minimum ventriculoatrial interval recorded in the esophagus (V-Aeso) exceeded 70 ms (four infants), transient bundle branch block during tachycardia prolonged the cycle length and the V-Aeso by 30 to 50 ms (three infants). Findings in these infants suggested prior episodes of prolonged tachycardia as the probable etiology of the cardiovascular collapse.

  3. Dynamic hydrolase activities precede hypersensitive tissue collapse in tomato seedlings.

    Science.gov (United States)

    Sueldo, Daniela; Ahmed, Ali; Misas-Villamil, Johana; Colby, Tom; Tameling, Wladimir; Joosten, Matthieu H A J; van der Hoorn, Renier A L

    2014-08-01

    Hydrolases such as subtilases, vacuolar processing enzymes (VPEs) and the proteasome play important roles during plant programmed cell death (PCD). We investigated hydrolase activities during PCD using activity-based protein profiling (ABPP), which displays the active proteome using probes that react covalently with the active site of proteins. We employed tomato (Solanum lycopersicum) seedlings undergoing synchronized hypersensitive cell death by co-expressing the avirulence protein Avr4 from Cladosporium fulvum and the tomato resistance protein Cf-4. Cell death is blocked in seedlings grown at high temperature and humidity, and is synchronously induced by decreasing temperature and humidity. ABPP revealed that VPEs and the proteasome are not differentially active, but that activities of papain-like cysteine proteases and serine hydrolases, including Hsr203 and P69B, increase before hypersensitive tissue collapse, whereas the activity of a carboxypeptidase-like enzyme is reduced. Similar dynamics were observed for these enzymes in the apoplast of tomato challenged with C. fulvum. Unexpectedly, these challenged plants also displayed novel isoforms of secreted putative VPEs. In the absence of tissue collapse at high humidity, the hydrolase activity profile is already altered completely, demonstrating that changes in hydrolase activities precede hypersensitive tissue collapse. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.

  4. Dark sector impact on gravitational collapse of an electrically charged scalar field

    Energy Technology Data Exchange (ETDEWEB)

    Nakonieczna, Anna [Institute of Physics, Maria Curie-Skłodowska University,Plac Marii Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Institute of Agrophysics, Polish Academy of Sciences,Doświadczalna 4, 20-290 Lublin (Poland); Rogatko, Marek [Institute of Physics, Maria Curie-Skłodowska University,Plac Marii Curie-Skłodowskiej 1, 20-031 Lublin (Poland); Nakonieczny, Łukasz [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw,Pasteura 5, 02-093 Warszawa (Poland)

    2015-11-04

    Dark matter and dark energy are dominating components of the Universe. Their presence affects the course and results of processes, which are driven by the gravitational interaction. The objective of the paper was to examine the influence of the dark sector on the gravitational collapse of an electrically charged scalar field. A phantom scalar field was used as a model of dark energy in the system. Dark matter was modeled by a complex scalar field with a quartic potential, charged under a U(1)-gauge field. The dark components were coupled to the electrically charged scalar field via the exponential coupling and the gauge field-Maxwell field kinetic mixing, respectively. Complete non-linear simulations of the investigated process were performed. They were conducted from regular initial data to the end state, which was the matter dispersal or a singularity formation in a spacetime. During the collapse in the presence of dark energy dynamical wormholes and naked singularities were formed in emerging spacetimes. The wormhole throats were stabilized by the violation of the null energy condition, which occurred due to a significant increase of a value of the phantom scalar field function in its vicinity. The square of mass parameter of the dark matter scalar field potential controlled the formation of a Cauchy horizon or wormhole throats in the spacetime. The joint impact of dark energy and dark matter on the examined process indicated that the former decides what type of an object forms, while the latter controls the amount of time needed for the object to form. Additionally, the dark sector suppresses the natural tendency of an electrically charged scalar field to form a dynamical Reissner-Nordström spacetime during the gravitational collapse.

  5. How Hives Collapse: Allee Effects, Ecological Resilience, and the Honey Bee.

    Directory of Open Access Journals (Sweden)

    Brian Dennis

    Full Text Available We construct a mathematical model to quantify the loss of resilience in collapsing honey bee colonies due to the presence of a strong Allee effect. In the model, recruitment and mortality of adult bees have substantial social components, with recruitment enhanced and mortality reduced by additional adult bee numbers. The result is an Allee effect, a net per-individual rate of hive increase that increases as a function of adult bee numbers. The Allee effect creates a critical minimum size in adult bee numbers, below which mortality is greater than recruitment, with ensuing loss of viability of the hive. Under ordinary and favorable environmental circumstances, the critical size is low, and hives remain large, sending off viably-sized swarms (naturally or through beekeeping management when hive numbers approach an upper stable equilibrium size (carrying capacity. However, both the lower critical size and the upper stable size depend on many parameters related to demographic rates and their enhancement by bee sociality. Any environmental factors that increase mortality, decrease recruitment, or interfere with the social moderation of these rates has the effect of exacerbating the Allee effect by increasing the lower critical size and substantially decreasing the upper stable size. As well, the basin of attraction to the upper stable size, defined by the model potential function, becomes narrower and shallower, indicating the loss of resilience as the hive becomes subjected to increased risk of falling below the critical size. Environmental effects of greater severity can cause the two equilibria to merge and the basin of attraction to the upper stable size to disappear, resulting in collapse of the hive from any initial size. The model suggests that multiple proximate causes, among them pesticides, mites, pathogens, and climate change, working singly or in combinations, could trigger hive collapse.

  6. Structural and Seafloor Morphological Evidence for Collapse of the Nankai Trough Accretionary Prism

    Science.gov (United States)

    Curewitz, D.; Harris, R.; Kimura, G.; Screaton, E. J.; 314/315/316 Science Party, I.

    2008-12-01

    Recent models for the evolution and structural architecture of accretionary prisms have suggested that the overall behavior of these systems is governed by the dynamic relationship between the geometry of the basal thrusts and the shape of the seafloor, coupled with the state of the basal thrust (slipping, creeping, or locked), the mechanical characteristics of the prism rocks, and the structure of the internal parts of the prism. In the NanTroSEIZE study area, the seafloor along the outer edge of the accretionary prism adjacent to the trench (the prism toe) exhibits a number of features indicative of gravitational collapse, including several listric headwall scarps and associated debris-slide and landslide deposits. Cores collected from the toe of the prism during IODP Expedition 316 contain a wide array of structures, including several populations of faults exhibiting orientations consistent with the geometry of the inferred headwall scarps. Borehole temperature measurements collected near the toe of the prism (and near areas affected by these inferred submarine slides) give rise to anomalously low heat flow values. Taken together, these data suggest that the toe of the Nankai Accretionary Prism offshore the Kii Peninsula, Japan, is currently in a state of collapse. The expression of this mechanical state is found in the along-trench succession of landslide andother gravitational collapse features, the arcuate or listric fault systems that form the detachment surface for these slides, and the inferred infiltration of seawater into the prism via these fault systems, resulting in drastic (and ongoing) cooling of the prism toe by advecting seawater.

  7. Climate Contributions to Vegetation Variations in Central Asian Drylands: Pre- and Post-USSR Collapse

    Directory of Open Access Journals (Sweden)

    Yu Zhou

    2015-03-01

    Full Text Available Central Asia comprises a large fraction of the world’s drylands, known to be vulnerable to climate change. We analyzed the inter-annual trends and the impact of climate variability in the vegetation greenness for Central Asia from 1982 to 2011 using GIMMS3g normalized difference vegetation index (NDVI data. In our study, most areas showed an increasing trend during 1982–1991, but experienced a significantly decreasing trend for 1992–2011. Vegetation changes were closely coupled to climate variables (precipitation and temperature during 1982–1991 and 1992–2011, but the response trajectories differed between these two periods. The warming trend in Central Asia initially enhanced the vegetation greenness before 1991, but the continued warming trend subsequently became a suppressant of further gains in greenness afterwards. Precipitation expanded its influence on larger vegetated areas in 1992–2011 when compared to 1982–1991. Moreover, the time-lag response of plants to rainfall tended to increase after 1992 compared to the pre-1992 period, indicating that plants might have experienced functional transformations to adapt the climate change during the study period. The impact of climate on vegetation was significantly different for the different sub-regions before and after 1992, coinciding with the collapse of the Union of Soviet Socialist Republics (USSR. It was suggested that these spatio-temporal patterns in greenness change and their relationship with climate change for some regions could be explained by the changes in the socio-economic structure resulted from the USSR collapse in late 1991. Our results clearly illustrate the combined influence of climatic/anthropogenic contributions on vegetation growth in Central Asian drylands. Due to the USSR collapse, this region represents a unique case study of the vegetation response to climate changes under different climatic and socio-economic conditions.

  8. Probing Water and CO2 Interactions at the Surface of Collapsed Titania Nanotubes Using IR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Kaustava Bhattacharyya

    2015-08-01

    Full Text Available Collapsed titania nanotubes (cTiNT were synthesized by the calcination of titania nanotubes (TiNT at 650 °C, which leads to a collapse of their tubular morphology, a substantial reduction in surface area, and a partial transformation of anatase to the rutile phase. There are no significant changes in the position of the XPS responses for Ti and O on oxidation or reduction of the cTiNTs, but the responses are more symmetric than those observed for TiNTs, indicating fewer surface defects and no change in the oxidation state of titanium on oxidative and/or reductive pretreatment. The interaction of H2O and CO2 with the cTiNT surface was studied. The region corresponding to OH stretching absorptions extends below 3000 cm−1, and thus is broader than is typically observed for absorptions of the OH stretches of water. The exchange of protons for deuterons on exposure to D2O leads to a depletion of this extended absorption and the appearance of new absorptions, which are compatible with deuterium exchange. We discuss the source of this extended low frequency OH stretching region and conclude that it is likely due to the hydrogen-bonded OH stretches. Interaction of the reduced cTiNTs with CO2 leads to a similar but smaller set of adsorbed carbonates and bicarbonates as reported for reduced TiNTs before collapse. Implications of these observations and the presence of proton sources leading to hydrogen bonding are discussed relative to potential chemical and photochemical activity of the TiNTs. These results point to the critical influence of defect structure on CO2 photoconversion.

  9. Graphene susceptibility in Holstein model

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.co [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Science and Nano Technology Research Center, Razi University, Kermanshah (Iran, Islamic Republic of)

    2011-06-15

    We study the effects of the electron-phonon interaction on the temperature dependence of the orbital magnetic susceptibility of monolayer graphene. We use the linear response theory and Green's function formalism within the Holstein Hamiltonian model. The results show that the effects of the electron-phonon interaction on the susceptibility of graphene sheet have different behaviors in two temperature regions. In the low temperature region, susceptibility increases when the electron-phonon coupling strength increases. On the other hand, the susceptibility reduces with increasing the electron-phonon coupling strength in the high temperature region. - Highlights: Effect of electron-phonon interaction on the susceptibility of graphene is studied. Linear response theory and Green's function technique in Holstein model are used. Effect of electron-phonon on susceptibility has different behaviors in two temperature regions.

  10. Topological susceptibility from slabs

    Energy Technology Data Exchange (ETDEWEB)

    Bietenholz, Wolfgang [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Forcrand, Philippe de [Institute for Theoretical Physics, ETH Zürich,CH-8093 Zürich (Switzerland); CERN, Physics Department, TH Unit, CH-1211 Geneva 23 (Switzerland); Gerber, Urs [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, Distrito Federal, C.P. 04510 (Mexico); Instituto de Física y Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo,Edificio C-3, Apdo. Postal 2-82, Morelia, Michoacán, C.P. 58040 (Mexico)

    2015-12-14

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility χ{sub t}. In principle it seems straightforward to measure χ{sub t} by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure χ{sub t} even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of χ{sub t}, as we demonstrate with numerical results for non-linear σ-models.

  11. Topological Susceptibility from Slabs

    CERN Document Server

    Bietenholz, Wolfgang; Gerber, Urs

    2015-01-01

    In quantum field theories with topological sectors, a non-perturbative quantity of interest is the topological susceptibility chi_t. In principle it seems straightforward to measure chi_t by means of Monte Carlo simulations. However, for local update algorithms and fine lattice spacings, this tends to be difficult, since the Monte Carlo history rarely changes the topological sector. Here we test a method to measure chi_t even if data from only one sector are available. It is based on the topological charges in sub-volumes, which we denote as slabs. Assuming a Gaussian distribution of these charges, this method enables the evaluation of chi_t, as we demonstrate with numerical results for non-linear sigma-models.

  12. Biological indicators and biological indication

    Energy Technology Data Exchange (ETDEWEB)

    Haseloff, H.P.

    1982-02-01

    Pollutants in the environment cause more and more situations of burden for living beings. In certain organisms, i.e. in biological indicators, there is a correlation between the extent of the damage and the degree of the burden. That is why environmental burdens can be recognized and, in part, be quantitatively recorded. Depending of the choice of materials and the damage parameters the respective differentiated statements can be made. Compared to technical measuring stations biological indicators facilitate the assessment of situations of burden with the help of biological-ecological parameters.

  13. Simple model of the Rayleigh-Taylor instability, collapse, and structural elements

    Science.gov (United States)

    Goncharov, V. P.; Pavlov, V. I.

    2013-08-01

    The mechanisms and structural elements of the Rayleigh-Taylor instability whose evolution results in the occurrence of the collapse have been studied in the scope of the rotating shallow water model with horizontal density gradient. Analysis of the instability mechanism shows that two collapse scenarios are possible. One scenario implies anisotropic collapse during which the contact area of a collapsing fragment with the bottom contracts into a spinning segment. The other implies isotropic contracting of the area into a point. The rigorous integral criteria and power laws of collapses are found.

  14. Structural elements of collapses in shallow water flows with horizontally nonuniform density

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. P., E-mail: v.goncharov@rambler.ru [Russian Academy of Sciences, Obukhov Institute of Atmospheric Physics (Russian Federation); Pavlov, V. I., E-mail: Vadim.Pavlov@univ-lille1.fr [Universite de Lille 1, UFR de Mathematiques Pures et Appliquees-LML UMR 8107 (France)

    2013-10-15

    The mechanisms and structural elements of instability whose evolution results in the occurrence of the collapse are studied in the scope of the rotating shallow water model with a horizontally nonuniform density. The diagram stability based on the integral collapse criterion is suggested to explain system behavior in the space of constants of motion. Analysis of the instability shows that two collapse scenarios are possible. One scenario implies anisotropic collapse during which the contact area of a collapsing drop-like fragment with the bottom contracts into a rotating segment. The other implies isotropic contraction of the area into a point.

  15. A Case Study in Archaeoseismology: the Collapses of the Temples at Selinunte (South-Western Sicily)

    Science.gov (United States)

    Guidoboni, E.

    2001-12-01

    This work presents the results of a research that was carried out to further our knowledge of the active faults in south-western Sicily. The only seismic event of particular significance that is known to have occurred is that of 15 January 1968 (Io= XMCS, Me 6.5) in the Belice valley. The archaeological park of Selinunte, the largest in the Mediterranean area, with its great temples and evidence of spectacular collapses, has been taken as a source of information capable of analysis by means of the methodological approach of archaeoseismology. The identification of the seismic indicators at Selinunte necessitated a detailed analysis of both old and new archaeological evidence, together with a critical re-examination of all the archaeological literature and existing documents dating from to the eighteenth century, together with travelers' accounts of that time. The history of the archaeological deposits, spoliation, and excavations has been reconstructed. These data are reinterpreted in the light of both the new discoveries of the most recent research, and of a number of methodological criteria already used in previous works on archaeoseismology. This long and complex analysis was carried out in 1998-99 with Anna Muggia, Clemente Marconi and Enzo Boschi in the research programme of the Istituto Nazionale di Geofisica e Vulcanologia. It resulted in the identification of two seismic events that struck Selinunte and led to the collapse of the temples. The chronology of the earthquakes can be dated, for the first, to a period between the fourth and third century BC; for the second, to a period between the sixth and the thirteen century AD. Although the time span proposed, particularly for the second earthquake, is very broad, it does not mean that this earthquake is in anyway hypothetical from a geophysical point of view. Its traces are clear, but the long periods when the site was abandoned mitigate against the fixing of a precise date for the event. In order to reach

  16. Mapping and modelling of collapse sinkholes in soluble rock: the Münsterdorf site, northern Germany

    Science.gov (United States)

    Kaufmann, Georg; Romanov, Douchko

    2017-04-01

    Münsterdorf is a small village in the north of Hamburg, located along the northern rim of a salt diapir. The Permian rocks are uplifted and overlying rocks such as the cretaceous limestone, normally in several kilometres depth, have been pushed up close to the surface. In Münsterdorf, the cretaceous limestone can be found in around 20 m depth, and about 2 km further south, cretaceous limestones are quarried in a large open-pit mine. Since 2004, collapse sinkholes form on a sporting ground in Münsterdorf, with a frequency of about 1 per year, about 2-3 m in diameter and 3-5 m deep. The collapse sinkholes do not reach the underlying limestone, but seem to be related to accelerated dissolution in that formation. Above the cretacious limestone, quaternary gravels and glacial marls provide a non-soluble, but permeable and heterogeneous cover of about 20 m thickness. We have mapped the sporting ground and its vicinity with gravity (GRAV), electrical resistivity imaging (ERI), self-potential measurements (SP), and ground-penetrating radar (GPR). While GRAV and SP is fairly unspectacular, the ERI profiles indicate a significant change in the surface layer, from thin and irregular in the northern part to thicker and more homogeneous in the southern part of the sporting ground. GPR profiles confirm this result. With numerically modelling the evolution of flow and porosity in the cretaceous limestone, we discuss the potential cause of the sinkhole formation and its sudden onset.

  17. Increased stress among women following an economic collapse--a prospective cohort study.

    Science.gov (United States)

    Hauksdóttir, Arna; McClure, Christopher; Jonsson, Stefan Hrafn; Olafsson, Orn; Valdimarsdóttir, Unnur A

    2013-05-01

    There is a scarcity of data on mental health effects of the global economic recession. In this study, we investigated potential change in self-reported levels of psychological stress in the Icelandic population as a result of the major national economic collapse that occurred in 2008. We used a national cohort of 3,755 persons who responded to a survey administered in 2007 and 2009, including demographic questions and a stress measure (the 4-item Perceived Stress Scale). We used repeated-measures analysis of variance and logistic regression models to assess change in mean stress levels and risk of high stress levels (>90th percentile) in 2009 as compared with 2007. Age-adjusted mean stress levels increased between 2007 and 2009 (P = 0.004), though the increase was observed only for women (P = 0.003), not for men (P = 0.34). Similarly, the odds ratios for experiencing high stress levels were increased only among women (odds ratio (OR) = 1.37), especially among women who were unemployed (OR = 3.38), students (OR = 2.01), had middle levels of education (OR = 1.65), or were in the middle income bracket (OR = 1.59). The findings indicate that psychological stress may have increased following the economic collapse in Iceland, particularly among females in economically vulnerable groups.

  18. Metaphyseal bone collapse mimicking slipped capital femoral epiphysis in severe renal osteodystrophy.

    Science.gov (United States)

    Takao, Masaki; Hashimoto, Jun; Sakai, Takashi; Nishii, Takashi; Sugano, Nobuhiko; Yoshikawa, Hideki

    2012-11-01

    Slipped capital femoral epiphysis is a well-recognized skeletal complication of renal osteodystrophy in adolescence, which is distinct from idiopathic slipped capital femoral epiphysis in its etiology. We report a case of severe mixed-type renal osteodystrophy with metaphyseal bone collapse that mimicked slipped capital femoral epiphyses. Case history, laboratory and radiological evaluation, and bone biopsies are discussed. A 14-yr-old girl presented with left hip pain showing bilateral metaphyseal bone collapse accompanied with posterior-inferior displacement of capital femoral epiphyses after 2.5 yr of GH treatment. Blood chemistry, showing high levels of alkaline phosphatase and PTH, and a transiliac bone biopsy, indicating severe osteomalacia with osteitis fibrosa, along with serial computed tomography images of the hips from the presymptomatic stage, led to accurate diagnosis and successful treatment by administration of high-dose vitamin D. This case emphasizes the importance of controlling hyperparathyroidism well in children with chronic renal insufficiency, particularly at adolescence before initiating GH treatment. When children with renal insufficiency present with displacement of capital femoral epiphysis, it is necessary to evaluate the serum levels of alkaline phosphatase and PTH and metaphyseal bone quality below the physis.

  19. Spatial distribution of sequential ventilation during mechanical ventilation of the uninjured lung: an argument for cyclical airway collapse and expansion

    Directory of Open Access Journals (Sweden)

    Altemeier William A

    2010-05-01

    Full Text Available Abstract Background Ventilator-induced lung injury (VILI is a recognized complication of mechanical ventilation. Although the specific mechanism by which mechanical ventilation causes lung injury remains an active area of study, the application of positive end expiratory pressure (PEEP reduces its severity. We have previously reported that VILI is spatially heterogeneous with the most severe injury in the dorsal-caudal lung. This regional injury heterogeneity was abolished by the application of PEEP = 8 cm H2O. We hypothesized that the spatial distribution of lung injury correlates with areas in which cyclical airway collapse and recruitment occurs. Methods To test this hypothesis, rabbits were mechanically ventilated in the supine posture, and regional ventilation distribution was measured under four conditions: tidal volumes (VT of 6 and 12 ml/kg with PEEP levels of 0 and 8 cm H2O. Results We found that relative ventilation was sequentially redistributed towards dorsal-caudal lung with increasing tidal volume. This sequential ventilation redistribution was abolished with the addition of PEEP. Conclusions These results suggest that cyclical airway collapse and recruitment is regionally heterogeneous and spatially correlated with areas most susceptible to VILI.

  20. Microwave susceptibility experiments

    Energy Technology Data Exchange (ETDEWEB)

    McConaghy, C.

    1984-05-29

    In certain experimental environments, systems can be affected or damaged by microwave pulses. I have conducted tests at LLNL to understand the phenomenology of microwave susceptibility of system components and subsystem components. To date, my experiments have concentrated on bipolar transistors, similar to what might be used in discrete analog circuits, and on CMOS RAM chips, which might be used in a computer memory system. I observed a decrease in failure energies for both the transistor and the integrated curcuit as I shortened the microwave pulse width. An S band (2.86 GHz) transmit/receive (T/R) tube has also been tested both at S band and at X band (8.16 GHz). The S band pulse had limitations in rise-time from zero power, which had an effect on the amount of power that could be transmitted through the T/R tube, as much as 0.7% of the incident power passed through the tube. All tests were conducted in closed-waveguide or coax test-fixtures, in contrast to the anechoic chambers utilized by other experimenters. I have used both S band and X band Klystron generators. For very high power (greater than 1 MW), I used an additional pulse-compression cavity at S band. Other subsystem components such as an X band mixer and an X band T/R tube will be tested in the future. 8 references.

  1. [Antimicrobial susceptibility cumulative reports].

    Science.gov (United States)

    Canut-Blasco, Andrés; Calvo, Jorge; Rodríguez-Díaz, Juan Carlos; Martínez-Martínez, Luis

    2016-10-01

    Cumulative reports on antimicrobial susceptibility tests data are important for selecting empirical treatments, as an educational tool in programs on antimicrobial use, and for establishing breakpoints defining clinical categories. These reports should be based on data validated by clinical microbiologists using diagnostic samples (not surveillance samples). In order to avoid a bias derived from including several isolates obtained from the same patient, it is recommended that, for a defined period, only the first isolate is counted. A minimal number of isolates per species should be presented: a figure of >=30 isolates is statistically acceptable. The report is usually presented in a table format where, for each cell, information on clinically relevant microorganisms-antimicrobial agents is presented. Depending on particular needs, multiple tables showing data related to patients, samples, services or special pathogens can be prepared. Copyright © 2015 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

  2. Extreme measures: field amputation on the living and dismemberment of the deceased to extricate individuals entrapped in collapsed structures.

    Science.gov (United States)

    Macintyre, Anthony; Kramer, Efraim B; Petinaux, Bruno; Glass, Trevor; Tate, Charmaine M

    2012-12-01

    Collapsed structures, typically as a result of earthquakes, may result in individuals entrapped by their limbs under heavy structural elements. In addition, access to living persons may be blocked by the deceased. Individuals are often critically ill by the time they are found, and rapid extrication is warranted. This and other factors may necessitate field amputation of an extremity on a living person or dismemberment of the deceased to achieve a rescue. Although case reports have described industrial, mining, and transportation accidents, few discuss this potential in collapsed structures. Also, few specifically outline the indications or the decision process and associated administrative procedures that should be addressed before conducting these procedures. This report presents a review of the literature along with a limited case series. A discussion regarding relevant decision making is provided to encourage the development of protocols. An international consensus statement on these procedures is provided.

  3. Combined rock slope stability and shallow landslide susceptibility assessment of the Jasmund cliff area (Rügen Island, Germany

    Directory of Open Access Journals (Sweden)

    A. Günther

    2009-05-01

    Full Text Available In this contribution we evaluated both the structurally-controlled failure susceptibility of the fractured Cretaceous chalk rocks and the topographically-controlled shallow landslide susceptibility of the overlying glacial sediments for the Jasmund cliff area on Rügen Island, Germany. We employed a combined methodology involving spatially distributed kinematical rock slope failure testing with tectonic fabric data, and both physically- and inventory-based shallow landslide susceptibility analysis. The rock slope failure susceptibility model identifies areas of recent cliff collapses, confirming its value in predicting the locations of future failures. The model reveals that toppling is the most important failure type in the Cretaceous chalk rocks of the area. The shallow landslide susceptibility analysis involves a physically-based slope stability evaluation which utilizes material strength and hydraulic conductivity data, and a bivariate landslide susceptibility analysis exploiting landslide inventory data and thematic information on ground conditioning factors. Both models show reasonable success rates when evaluated with the available inventory data, and an attempt was made to combine the individual models to prepare a map displaying both terrain instability and landslide susceptibility. This combination highlights unstable cliff portions lacking discrete landslide areas as well as cliff sections highly affected by past landslide events. Through a spatial integration of the rock slope failure susceptibility model with the combined shallow landslide assessment we produced a comprehensive landslide susceptibility map for the Jasmund cliff area.

  4. Collapsed scrums and collision tackles: what is the injury risk?

    Science.gov (United States)

    Roberts, Simon P; Trewartha, Grant; England, Mike; Stokes, Keith A

    2015-04-01

    To establish the propensity for specific contact events to cause injury in rugby union. Medical staff at participating English community-level rugby clubs reported any injury resulting in the absence for one match or more from the day of the injury during the 2009/2010 (n=46), 2010/2011 (n=67) and 2011/2012 (n=76) seasons. Injury severity was defined as the number of matches missed. Thirty community rugby matches were filmed and the number of contact events (tackles, collision tackles, rucks, mauls, lineouts and scrums) recorded. Of 370 (95% CI 364 to 378) contact events per match, 141 (137 to 145) were tackles, 115 (111 to 119) were rucks and 32 (30 to 33) were scrums. Tackles resulted in the greatest propensity for injury (2.3 (2.2 to 2.4) injuries/1000 events) and the greatest severity (16 (15 to 17) weeks missed/1000 events). Collision tackles (illegal tackles involving a shoulder charge) had a propensity for injury of 15 (12.4 to 18.3) injuries/1000 events and severity was 92 (75 to 112) weeks missed/1000 events, both of which were higher than any other event. Additional scrum analysis showed that only 5% of all scrums collapsed, but the propensity for injury was four times higher (2.9 (1.5 to 5.4) injuries/1000 events) and the severity was six times greater (22 (12 to 42) weeks missed/1000 events) than for non-collapsed scrums. Injury prevention in the tackle should focus on technique with strict enforcement of existing laws for illegal collision tackles. The scrum is a relatively controllable event and further attempts should be made to reduce the frequency of scrum collapse. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. Upper Airway Collapsibility and Genioglossus Activity in Adolescents during Sleep

    Science.gov (United States)

    Huang, Jingtao; Pinto, Swaroop J.; Yuan, Haibo; Katz, Eliot S.; Karamessinis, Laurie R.; Bradford, Ruth M.; Gallagher, Paul R.; Hannigan, James T.; Nixon, Thomas; Ward, Michelle B.; Lee, Yin N.; Marcus, Carole L.

    2012-01-01

    Study Objectives: Obese patients develop obstructive sleep apnea syndrome (OSAS), at least in part because of a narrowed upper airway. However, many obese adolescents do not develop OSAS, despite having a presumably narrower airway. The reasons for this phenomenon are unclear. The authors hypothesized that obese controls have a compensatory neuromuscular response to subatmospheric pressure loads during sleep, making them less likely to develop upper airway collapse. Design: Patients underwent pressure-flow measurements during sleep while wearing intraoral electrodes to measure genioglossal electromyography (EMGgg). Two techniques were applied to decrease nasal pressure (PN) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway. Setting: Sleep laboratory. Participants: There were 35 obese patients with OSAS, 28 obese controls, and 43 lean controls. Results: In the activated state, the two control groups had a flatter slope of the pressure-flow relationship and a more negative critical closing pressure (less collapsible) than the OSAS group. In the hypotonic state, the lean controls had a flatter slope of the pressure-flow relationship than the OSAS and obese control groups. In the activated state, the slope of EMGgg versus PN was greater in the obese control group than in the OSAS or lean control groups (P = 0.002 and P = 0.028, respectively); there were no differences in the hypotonic state. Conclusions: Obese controls have vigorous upper airway neuromuscular responses during sleep. Upper airway reflexes normally decline during adolescent development. It is speculated that obese adolescents without OSAS maintain protective upper airway reflexes during adolescent development, whereas those who go on to develop OSAS do not. Citation: Huang J; Pinto SJ; Yuan H; Katz ES; Karamessinis LR; Bradford RM; Gallagher PR; Hannigan JT; Nixon T; Ward MB; Lee YN; Marcus CL. Upper airway collapsibility and genioglossus activity in adolescents

  6. Single homopolypeptide chains collapse into mechanically rigid conformations

    Science.gov (United States)

    Dougan, Lorna; Li, Jingyuan; Badilla, Carmen L.; Berne, B. J.; Fernandez, Julio M.

    2009-01-01

    Huntington's disease is linked to the insertion of glutamine (Q) in the protein huntingtin, resulting in polyglutamine (polyQ) expansions that self-associate to form aggregates. While polyQ aggregation has been the subject of intense study, a correspondingly thorough understanding of individual polyQ chains is lacking. Here we demonstrate a single molecule force-clamp technique that directly probes the mechanical properties of single polyQ chains. We have made polyQ constructs of varying lengths that span the length range of normal and diseased polyQ expansions. Each polyQ construct is flanked by the I27 titin module, providing a clear mechanical fingerprint of the molecule being pulled. Remarkably, under the application of force, no extension is observed for any of the polyQ constructs. This is in direct contrast with the random coil protein PEVK of titin, which readily extends under force. Our measurements suggest that polyQ chains form mechanically stable collapsed structures. We test this hypothesis by disrupting polyQ chains with insertions of proline residues and find that their mechanical extensibility is sensitive to the position of the proline interruption. These experiments demonstrate that polyQ chains collapse to form a heterogeneous ensemble of conformations that are mechanically resilient. We further use a heat-annealing molecular dynamics protocol to extensively search the conformation space and find that polyQ can exist in highly mechanically stable compact globular conformations. The mechanical rigidity of these collapsed structures may exceed the functional ability of eukaryotic proteasomes, resulting in the accumulation of undigested polyQ sequences in vivo. PMID:19549822

  7. Crawling to collapse: ecologically unsound ornamental invertebrate fisheries.

    Directory of Open Access Journals (Sweden)

    Andrew Rhyne

    Full Text Available BACKGROUND: Fishery management has historically been an inexact and reactionary discipline, often taking action only after a critical stock suffers overfishing or collapse. The invertebrate ornamental fishery in the State of Florida, with increasing catches over a more diverse array of species, is poised for collapse. Current management is static and the lack of an adaptive strategy will not allow for adequate responses associated with managing this multi-species fishery. The last decade has seen aquarium hobbyists shift their display preference from fish-only tanks to miniature reef ecosystems that include many invertebrate species, creating increased demand without proper oversight. The once small ornamental fishery has become an invertebrate-dominated major industry supplying five continents. METHODOLOGY/PRINCIPAL FINDINGS: Here, we analyzed the Florida Marine Life Fishery (FLML landing data from 1994 to 2007 for all invertebrate species. The data were organized to reflect both ecosystem purpose (in the wild and ecosystem services (commodities for each reported species to address the following question: Are ornamental invertebrates being exploited for their fundamental ecosystem services and economic value at the expense of reef resilience? We found that 9 million individuals were collected in 2007, 6 million of which were grazers. CONCLUSIONS/SIGNIFICANCE: The number of grazers now exceeds, by two-fold, the number of specimens collected for curio and ornamental purposes altogether, representing a major categorical shift. In general, landings have increased 10-fold since 1994, though the number of licenses has been dramatically reduced. Thus, despite current management strategies, the FLML Fishery appears to be crawling to collapse.

  8. Toward Realistic Progenitors of Core-collapse Supernovae

    Science.gov (United States)

    Arnett, W. David; Meakin, Casey

    2011-06-01

    Two-dimensional (2D) hydrodynamical simulations of progenitor evolution of a 23 M sun star, close to core collapse (in ~1 hr in one dimension (1D)), with simultaneously active C, Ne, O, and Si burning shells, are presented and contrasted to existing 1D models (which are forced to be quasi-static). Pronounced asymmetries and strong dynamical interactions between shells are seen in 2D. Although instigated by turbulence, the dynamic behavior proceeds to sufficiently large amplitudes that it couples to the nuclear burning. Dramatic growth of low-order modes is seen as well as large deviations from spherical symmetry in the burning shells. The vigorous dynamics is more violent than that seen in earlier burning stages in the three-dimensional (3D) simulations of a single cell in the oxygen burning shell, or in 2D simulations not including an active Si shell. Linear perturbative analysis does not capture the chaotic behavior of turbulence (e.g., strange attractors such as that discovered by Lorenz), and therefore badly underestimates the vigor of the instability. The limitations of 1D and 2D models are discussed in detail. The 2D models, although flawed geometrically, represent a more realistic treatment of the relevant dynamics than existing 1D models, and present a dramatically different view of the stages of evolution prior to collapse. Implications for interpretation of SN1987A, abundances in young supernova remnants, pre-collapse outbursts, progenitor structure, neutron star kicks, and fallback are outlined. While 2D simulations provide new qualitative insight, fully 3D simulations are needed for a quantitative understanding of this stage of stellar evolution. The necessary properties of such simulations are delineated.

  9. Intrathoracic tracheal volume and collapsibility on inspiratory and end-expiratory ct scans correlations with lung volume and pulmonary function in 85 smokers.

    Science.gov (United States)

    Yamashiro, Tsuneo; San José Estépar, Raúl; Matsuoka, Shin; Bartholmai, Brian J; Ross, James C; Diaz, Alejandro; Murayama, Sadayuki; Silverman, Edwin K; Hatabu, Hiroto; Washko, George R

    2011-03-01

    To evaluate the correlations of tracheal volume and collapsibility on inspiratory and end-expiratory computed tomography (CT) with lung volume and with lung function in smokers. The institutional review board approved this study at each institution. 85 smokers (mean age 68, range 45-87 years; 40 females and 45 males) underwent pulmonary function tests and chest CT at full inspiration and end-expiration. On both scans, intrathoracic tracheal volume and lung volume were measured. Collapsibility of the trachea and the lung was expressed as expiratory/inspiratory (E/I) ratios of these volumes. Correlations of the tracheal measurements with the lung measurements and with lung function were evaluated by the linear regression analysis. Tracheal volume showed moderate or strong, positive correlations with lung volume on both inspiratory (r = 0.661, P volume showed a strong, positive correlation with the E/I ratio of lung volume (r = 0.711, P volume and the ratio of forced expiratory volume in the first second to forced vital capacity (r = -0.436, P volume and the ratio of residual volume to total lung capacity (r = 0.253, P = .02). Tracheal volume and collapsibility, measured by inspiratory and end-expiratory CT scans, is related to lung volume and collapsibility. The highly collapsed trachea on end-expiratory CT does not indicate more severe airflow limitation or air-trapping in smokers. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

  10. Results of Integrated Investigation of Collapse Sinkhole in Sarkayevo Village

    Directory of Open Access Journals (Sweden)

    O. N. Kovin

    2014-03-01

    Full Text Available The integrated investigations of karstic collapse sinkhole were conducted at the area of Sarkayevo village. The obtained hydrogeologic data show the local concentration of underground water flow at the investigated site, and high sulfate ion content in the water samples that suggests that a sinkhole is karstic in nature. Geophysical investigations allowed determining basic parameters of the site geological structure, to reveal the depth distribution of the disturbed ground in vicinity of the sinkhole, and delineate zones of different soil compaction. The recommendations for detail site study, aimed to the mitigation of further karst development hazards, are presented.

  11. Collapse arrest and soliton stabilization in nonlocal nonlinear media

    DEFF Research Database (Denmark)

    Bang, Ole; Krolikowski, Wieslaw; Wyller, John

    2002-01-01

    We investigate the properties of localized waves in cubic nonlinear materials with a symmetric nonlocal nonlinear response of arbitrary shape and degree of nonlocality, described by a general nonlocal nonlinear Schrodinger type equation. We prove rigorously by bounding the Hamiltonian...... that nonlocality of the nonlinearity prevents collapse in, e.g., Bose-Einstein condensates and optical Kerr media in all physical dimensions. The nonlocal nonlinear response must be symmetric and have a positive definite Fourier spectrum, but can otherwise be of completely arbitrary shape and degree of nonlocality...

  12. Shock wave emission during the collapse of cavitation bubbles

    Science.gov (United States)

    Garen, W.; Hegedűs, F.; Kai, Y.; Koch, S.; Meyerer, B.; Neu, W.; Teubner, U.

    2016-07-01

    Shock wave emission induced by intense laser pulses is investigated experimentally. The present work focuses on the conditions of shock wave emission in glycerine and distilled water during the first bubble collapse. Experimental investigations are carried out in liquids as a function of temperature and viscosity. Comparison is made with the theoretical work of Poritsky (Proc 1st US Natl Congress Appl Mech 813-821, 1952) and Brennen (Cavitation and bubble dynamics, Oxford University Press 1995). To the best knowledge of the authors, this is the first experimental verification of those theories.

  13. Scalar field collapse in a conformally flat spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarti, Soumya; Banerjee, Narayan [Indian Institute of Science Education and Research, Kolkata, Department of Physical Sciences, Mohanpur, West Bengal (India)

    2017-03-15

    The collapse scenario of a scalar field along with a perfect fluid distribution was investigated for a conformally flat spacetime. The theorem for the integrability of an anharmonic oscillator has been utilized. For a pure power-law potential of the form φ{sup n+1}, it was found that a central singularity is formed which is covered by an apparent horizon for n > 0 and n < -3. Some numerical results have also been presented for a combination of two different powers of φ in the potential. (orig.)

  14. Strategic Shock: The Collapse of the Soviet Union: 1989

    Science.gov (United States)

    2010-08-01

    sécurité de l’avenir ; ils allaient d’événements géopolitiques à des chocs dans les secteurs scientifique et technologique, environnemental et...the Soviet Union, the actual collapse of Soviet style communism in the late 1980’s and early 1990’s was by and large unanticipated in many important...unclassified) represented as (S), (C), (R), or (U). It is not necessary to include here abstracts in both official languages unless the text is

  15. Gravitational Dust Collapse in $f(R)$ Gravity

    CERN Document Server

    Shamir, M Farasat; Raza, Zahid

    2015-01-01

    This paper is devoted to investigate gravitational collapse of dust in metric $f(R)$ gravity. We take FRW metric for the interior region while the Schwarzchild spacetime is considered for the exterior region of a star. The junction conditions have been derived to match interior and exterior spacetimes. The assumption of constant scalar curvature is used to find a solution of field equations. Gravitational mass is found by using the junction conditions. It is concluded that the constant curvature term $f(R_0)$ plays the role of the cosmological constant involved in the field equations of general relativity.

  16. Asymptotics of weakly collapsing solutions of nonlinear Schroedinger equation

    CERN Document Server

    Ovchinnikov, Yu N

    2001-01-01

    One studied possible types of asymptotic behavior of weakly collapsing solution of the 3-rd nonlinear Schroedinger equation. It is shown that within left brace A, C sub 1 right brace parameter space there are two neighboring lines along which the amplitude of oscillation terms is exponentially small as to C sub 1 parameter. The same lines locates values of left brace A, C sub 1 right brace parameters at which the energy is equal to zero. With increase of C sub 1 parameter the accuracy of numerical determination of points with zero energy drops abruptly

  17. Gravitational Collapse and Shocks in Two-Phase Celestial Bodies

    Science.gov (United States)

    Greenfield, Michael

    2017-06-01

    The phenomenon of gravitational collapse (GC) is well-known in theoretical astro- and planetary physics. It occurs when the incompressibility of substances is unable to withstand the pressure due to gravitational forces in celestial bodies of sufficiently large mass. The GC never occurs in incompressible models - homogeneous or layered. This situation changes dramatically when different incompressible layers appear to be different phases of the same chemical substance and the mass exchange between the phases can occur due to phase transformation. The possibility of destabilization in such system becomes realistic, as it was first discovered in the Ramsey static analysis. We will present our generalization of the Ramsey's results using dynamic approach.

  18. Gravitational collapse of a cylindrical null shell in vacuum

    Directory of Open Access Journals (Sweden)

    S. Khakshournia

    2008-03-01

    Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

  19. Edifice growth and collapse of the Pliocene Mt. Kenya : Evidence of large scale debris avalanches on a high altitude glaciated volcano

    NARCIS (Netherlands)

    Schoorl, J. M.; Veldkamp, A.; Claessens, L.; van Gorp, W.; Wijbrans, J. R.

    2014-01-01

    The cyclic growth and destruction of the Late Cenozoic Stratovolcano Mt. Kenya have been reconstructed for its southeastern segment. At least three major debris avalanche deposits have been reconstructed and dated. The oldest deposits indicate an edifice collapse around 4.9 Ma (Ar-40/Ar-39),

  20. Edifice growth and collapse of the Pliocene Mt. Kenya: Evidence of large scale debris avalanches on a high altitude glaciated volcano

    NARCIS (Netherlands)

    Schoorl, J.M.; Veldkamp, A.; Claessens, L.F.G.; Gorp, van W.; Wijbrans, J.R.

    2014-01-01

    The cyclic growth and destruction of the Late Cenozoic Stratovolcano Mt. Kenya have been reconstructed for its southeastern segment. At least three major debris avalanche deposits have been reconstructed and dated. The oldest deposits indicate an edifice collapse around 4.9 Ma (40Ar/39Ar), followed

  1. DETERMINACIÓN DE LA SUSCEPTIBILIDAD A DROGAS DE PRIMERA LÍNEA EN AISLAMIENTOS DE MYCOBACTERIUM TUBERCULOSIS POR LA TÉCNICA DEL TUBO INDICADOR DE CRECIMIENTO MICOBACTERIANO Determining the susceptibility to first-line drugs in M. tuberculosis isolates using the mycobacteria growth indicator tube method

    Directory of Open Access Journals (Sweden)

    Claudia Rocío Sierra Parada

    2008-03-01

    etambutol.Background. The appearance of Mycobacterium tuberculosis isolates resistant to drugs has triggered the search for quicker and more reliable methods to determine the susceptibility to anti-tuberculosis drugs. Objective. To evaluate the susceptibility of M. tuberculosis isolates to anti-tuberculosis first line drugs by Mycobacterium growth indicator tube method (MGIT. Materials and methods. Forty-nine isolates of M. tuberculosis were tested, coming from the Mycobacteriology Laboratory of Microbiology Department of the Universidad Nacional de Colombia. The MGIT method was evaluated and compared in order to determine resistance or susceptibility to rifampicin, isoniazid, ethambutol and streptomycin with the gold standard method, the multiple proportion method (PM. Results. With the PM method, of 49 isolates, 26 (53.0% were sensitive to all four antibiotics, 12 (24.5% were resistant to one antibiotic and 11 (22.5% to more than one antibiotic. Using the MGIT method, of 49 isolates, 31 (63.3% were sensitive to all four antibiotics, 8 (16.3% were resistant to one antibiotic and 10 (20.6% were resistant to more than one antibiotic. The concordance percentages observed oscillated between 83.7% and 97.9% and the kappa index was between 0.61 and 0.83 for the different antibiotics analyzed. The sensitivity of the MGIT method to the rifampicin, isoniazid, ethambutol and streptomycin was of 88.9, 95.2, 62.5 and 58% respectively and specifity was of 97.7, 92.3, 98.8 y 98.4% respectively. Using the MGIT method, isolates resistant to M. tuberculosis were determined in an average time of 7.85 days. Conclusions. The MGIT method permits obtaining reliable results in less time than conventional methods with isoniazid and rifampicin which are the antibiotics that determine the multi-resistance of M tuberculosis and to a lesser degree to streptomycin and ethambutol.

  2. Pregnancy-Induced Hypertensive Disorders before and after a National Economic Collapse: A Population Based Cohort Study.

    Directory of Open Access Journals (Sweden)

    Védís Helga Eiríksdóttir

    Full Text Available Data on the potential influence of macroeconomic recessions on maternal diseases during pregnancy are scarce. We aimed to assess potential change in prevalence of pregnancy-induced hypertensive disorders (preeclampsia and gestational hypertension during the first years of the major national economic recession in Iceland, which started abruptly in October 2008.Women whose pregnancies resulted in live singleton births in Iceland in 2005-2012 constituted the study population (N = 35,211. Data on pregnancy-induced hypertensive disorders were obtained from the Icelandic Medical Birth Register and use of antihypertensive drugs during pregnancy, including β-blockers and calcium channel blockers, from the Icelandic Medicines Register. With the pre-collapse period as reference, we used logistic regression analysis to assess change in pregnancy-induced hypertensive disorders and use of antihypertensives during the first four years after the economic collapse, adjusting for demographic and pregnancy characteristics, taking aggregate economic indicators into account. Compared with the pre-collapse period, we observed an increased prevalence of gestational hypertension in the first year following the economic collapse (2.4% vs. 3.9%; adjusted odds ratio [aOR] 1.47; 95 percent confidence interval [95%CI] 1.13-1.91 but not in the subsequent years. The association disappeared completely when we adjusted for aggregate unemployment rate (aOR 1.04; 95% CI 0.74-1.47. Similarly, there was an increase in prescription fills of β-blockers in the first year following the collapse (1.9% vs.3.1%; aOR 1.43; 95% CI 1.07-1.90, which disappeared after adjusting for aggregate unemployment rate (aOR 1.05; 95% CI 0.72-1.54. No changes were observed for preeclampsia or use of calcium channel blockers between the pre- and post-collapse periods.Our data suggest a transient increased risk of gestational hypertension and use of β-blockers among pregnant women in Iceland in the

  3. Pregnancy-Induced Hypertensive Disorders before and after a National Economic Collapse: A Population Based Cohort Study.

    Science.gov (United States)

    Eiríksdóttir, Védís Helga; Valdimarsdóttir, Unnur Anna; Ásgeirsdóttir, Tinna Laufey; Hauksdóttir, Arna; Lund, Sigrún Helga; Bjarnadóttir, Ragnheiður Ingibjörg; Cnattingius, Sven; Zoëga, Helga

    2015-01-01

    Data on the potential influence of macroeconomic recessions on maternal diseases during pregnancy are scarce. We aimed to assess potential change in prevalence of pregnancy-induced hypertensive disorders (preeclampsia and gestational hypertension) during the first years of the major national economic recession in Iceland, which started abruptly in October 2008. Women whose pregnancies resulted in live singleton births in Iceland in 2005-2012 constituted the study population (N = 35,211). Data on pregnancy-induced hypertensive disorders were obtained from the Icelandic Medical Birth Register and use of antihypertensive drugs during pregnancy, including β-blockers and calcium channel blockers, from the Icelandic Medicines Register. With the pre-collapse period as reference, we used logistic regression analysis to assess change in pregnancy-induced hypertensive disorders and use of antihypertensives during the first four years after the economic collapse, adjusting for demographic and pregnancy characteristics, taking aggregate economic indicators into account. Compared with the pre-collapse period, we observed an increased prevalence of gestational hypertension in the first year following the economic collapse (2.4% vs. 3.9%; adjusted odds ratio [aOR] 1.47; 95 percent confidence interval [95%CI] 1.13-1.91) but not in the subsequent years. The association disappeared completely when we adjusted for aggregate unemployment rate (aOR 1.04; 95% CI 0.74-1.47). Similarly, there was an increase in prescription fills of β-blockers in the first year following the collapse (1.9% vs.3.1%; aOR 1.43; 95% CI 1.07-1.90), which disappeared after adjusting for aggregate unemployment rate (aOR 1.05; 95% CI 0.72-1.54). No changes were observed for preeclampsia or use of calcium channel blockers between the pre- and post-collapse periods. Our data suggest a transient increased risk of gestational hypertension and use of β-blockers among pregnant women in Iceland in the first and most

  4. [Antimicrobial susceptibility in Chile 2012].

    Science.gov (United States)

    Cifuentes-D, Marcela; Silva, Francisco; García, Patricia; Bello, Helia; Briceño, Isabel; Calvo-A, Mario; Labarca, Jaime

    2014-04-01

    Bacteria antimicrobial resistance is an uncontrolled public health problem that progressively increases its magnitude and complexity. The Grupo Colaborativo de Resistencia, formed by a join of experts that represent 39 Chilean health institutions has been concerned with bacteria antimicrobial susceptibility in our country since 2008. In this document we present in vitro bacterial susceptibility accumulated during year 2012 belonging to 28 national health institutions that represent about 36% of hospital discharges in Chile. We consider of major importance to report periodically bacteria susceptibility so to keep the medical community updated to achieve target the empirical antimicrobial therapies and the control measures and prevention of the dissemination of multiresistant strains.

  5. Collapsing vortex filaments and the spectrum of quantum turbulence

    Science.gov (United States)

    Andryushchenko, V. A.; Nemirovskii, S. K.

    2017-01-01

    The method of correlation functions and the method of quantum vortex configurations are used to calculate the energy spectrum of a three-dimensional velocity field that is induced by collapsing (immediately before reconnection) vortex filaments. The formulation of this problem is motivated by the idea of modeling classical turbulence by a set of chaotic quantized vortex filaments. Among the various arguments that support the idea of quasi-classical behavior for quantum turbulence, the most persuasive is probably the resulting Kolmogorov energy spectrum resembling E ( k ) ∝ k - 5 / 3 that was obtained in a number of numerical studies. Another goal is associated with an important and intensely studied theme that relates to the role of hydrodynamic collapse in the formation of turbulence spectra. Calculations have demonstrated that vortex filaments create a velocity field at the moment of contact, which has a singularity. This configuration of vortex filaments generates the spectrum E(k), which bears the resemblance to the Kolmogorov law. A possible cause for this observation is discussed, as well as the likely reasons behind any deviations. The obtained results are discussed from the perspective of both classical and quantum turbulence.

  6. Volcano collapse along the Aleutian Ridge (western Aleutian Arc

    Directory of Open Access Journals (Sweden)

    C. Montanaro

    2011-03-01

    Full Text Available The Aleutian Ridge, in the western part of the Aleutian Arc, consists of a chain of volcanic islands perched atop the crest of a submarine ridge with most of the active Quaternary stratocones or caldera-like volcanoes being located on the northern margins of the Aleutian Islands. Integrated analysis of marine and terrestrial data resulted in the identification and characterization of 17 extensive submarine debris avalanche deposits from 11 volcanoes. Two morphological types of deposits are recognizable, elongate and lobate, with primary controls on the size and distribution of the volcanic debris being the volume and nature of material involved, proportion of fine grained material, depth of emplacement and the paleo-bathymetry. Volume calculations show the amount of material deposited in debris avalanches is as much as three times larger than the amount of material initially involved in the collapse, suggesting the incorporation of large amounts of submarine material during transport. The orientation of the collapse events is influenced by regional fault systems underling the volcanoes. The western Aleutian Arc has a significant tsunamigenic potential and communities within the Aleutian Islands and surrounding areas of the North Pacific as well as shipping and fishing fleets that cross the North Pacific may be at risk during future eruptions in this area.

  7. Quantum self-gravitating collapsing matter in a quantum geometry

    CERN Document Server

    Campiglia, Miguel; Olmedo, Javier; Pullin, Jorge

    2016-01-01

    The problem of how space-time responds to gravitating quantum matter in full quantum gravity has been one of the main questions that any program of quantization of gravity should address. Here we analyze this issue by considering the quantization of a collapsing null shell coupled to spherically symmetric loop quantum gravity. We show that the constraint algebra of canonical gravity is Abelian both classically and when quantized using loop quantum gravity techniques. The Hamiltonian constraint is well defined and suitable Dirac observables characterizing the problem were identified at the quantum level. We can write the metric as a parameterized Dirac observable at the quantum level and study the physics of the collapsing shell and black hole formation. We show how the singularity inside the black hole is eliminated by loop quantum gravity and how the shell can traverse it. The construction is compatible with a scenario in which the shell tunnels into a baby universe inside the black hole or one in which it c...

  8. A study on cavity collapse for utilizing green implosion energy

    Science.gov (United States)

    Lee, Hyunhee; Gojani, Ardian; Han, Tae-Hee; Yoh, Jack

    2009-06-01

    The mechanical energy generated by laser-induced implosion and the dynamics between non-condensable gas and liquid are studied experimentally and numerically. We have designed a micro implosion piston (MIP) to utilize the energy of implosion for inducing a piston motion. The MIP has the shape of a cone and is filled with liquid at room temperature and a high pressure (˜ 6 bars). Focusing of a high power laser pulse inside the MIP leads to creation of several bubbles that expand and collapse with successive rebounds. The bubble-liquid interaction develops a micro- jet that destroys the symmetry of the bubble. This bubble implosion motion, induced by the pressure gradient across the cavity wall produces high pressures wave within a few nanoseconds. These pressure waves are affected by different conditions such as the distance between the bubble and piston head, the dimension of the MIP, and the pressure at which the MIP is driven. The radius of the bubble is measured by double exposure photography, while pressure histories are measured by hydrophones. We investigate the relationship between the radius of the bubble, the overpressure of the secondary shock wave and the motion of the micro piston, and compare it to numerical simulations. The aim is to reach a state inside the MIP that would cause a sustainable and efficient motion of piston through cavity collapse induced high pressure pulses.

  9. Collapsed state of polyglutamic acid results in amyloid spherulite formation.

    Science.gov (United States)

    Stehli, Daniel; Mulaj, Mentor; Miti, Tatiana; Traina, Joshua; Foley, Joseph; Muschol, Martin

    2015-01-01

    Self-assembly of proteins and peptides into amyloid fibrils involves multiple distinct intermediates and late-stage fibrillar polymorphs. Understanding the conditions and mechanisms that promote the formation of one type of intermediate and polymorph over the other represents a fundamental challenge. Answers to this question are also of immediate biomedical relevance since different amyloid aggregate species have been shown to have distinct pathogenic potencies. One amyloid polymorph that has received comparatively little attention are amyloid spherulites. Here we report that self-assembly of the intrinsically disordered polymer poly(L-glutamic) acid (PLE) can generate amyloid spherulites. We characterize spherulite growth kinetics, as well as the morphological, optical and tinctorial features of this amyloid polymorph previously unreported for PLE. We find that PLE spherulites share both tinctorial and structural characteristics with their amyloid fibril counterparts. Differences in PLE's molecular weight, polydispersity or chemistry could not explain the selective propensity toward either fibril or spherulite formation. Instead, we provide evidence that PLE polymers can exist in either a collapsed globule or an extended random coil conformation. The collapsed globule consistently produces spherulites while the extended coil assembles into disordered fibril bundles. This results suggests that these 2 PLE conformers directly affect the morphology of the resulting macroscopic amyloid assembly.

  10. The imprints of the last jets in core collapse supernovae

    Science.gov (United States)

    Bear, Ealeal; Grichener, Aldana; Soker, Noam

    2017-12-01

    We analyse the morphologies of three core collapse supernova remnants (CCSNRs) and the energy of jets in other CCSNRs and in Super Luminous Supernovae (SLSNe) of type Ib/Ic/IIb, and conclude that these properties are well explained by the last jets' episode as expected in the jet feedback explosion mechanism of core collapse supernovae (CCSNe). The presence of two opposite protrusions, termed ears, and our comparison of the CCSNR morphologies with morphologies of planetary nebulae strengthen the claim that jets play a major role in the explosion mechanism of CCSNe. We crudely estimate the energy that was required to inflate the ears in two CCSNRs and assume that the ears were inflated by jets. We find that the energies of the jets which inflated ears in 11 CCSNRs span a range that is similar to that of jets in some energetic CCSNe (SLSNe) and that this energy, only of the last jets' episode, is much less than the explosion energy. This finding is compatible with the jet feedback explosion mechanism of CCSNe, where only the last jets, which carry a small fraction of the total energy carried by earlier jets, are expected to influence the outer parts of the ejecta. We reiterate our call for a paradigm shift from neutrino-driven to jet-driven explosion models of CCSNe.

  11. Genetic signature of anthropogenic population collapse in orang-utans.

    Directory of Open Access Journals (Sweden)

    Benoît Goossens

    2006-02-01

    Full Text Available Great ape populations are undergoing a dramatic decline, which is predicted to result in their extinction in the wild from entire regions in the near future. Recent findings have particularly focused on African apes, and have implicated multiple factors contributing to this decline, such as deforestation, hunting, and disease. Less well-publicised, but equally dramatic, has been the decline in orang-utans, whose distribution is limited to parts of Sumatra and Borneo. Using the largest-ever genetic sample from wild orang-utan populations, we show strong evidence for a recent demographic collapse in North Eastern Borneo and demonstrate that this signature is independent of the mutation and demographic models used. This is the first demonstration that genetic data can detect and quantify the effect of recent, human-induced deforestation and habitat fragmentation on an endangered species. Because current demographic collapses are usually confounded by ancient events, this suggests a much more dramatic decline than demographic data alone and emphasises the need for major conservation efforts.

  12. Genetic Signature of Anthropogenic Population Collapse in Orang-utans.

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Great ape populations are undergoing a dramatic decline, which is predicted to result in their extinction in the wild from entire regions in the near future. Recent findings have particularly focused on African apes, and have implicated multiple factors contributing to this decline, such as deforestation, hunting, and disease. Less well-publicised, but equally dramatic, has been the decline in orang-utans, whose distribution is limited to parts of Sumatra and Borneo. Using the largest-ever genetic sample from wild orang-utan populations, we show strong evidence for a recent demographic collapse in North Eastern Borneo and demonstrate that this signature is independent of the mutation and demographic models used. This is the first demonstration that genetic data can detect and quantify the effect of recent, human-induced deforestation and habitat fragmentation on an endangered species. Because current demographic collapses are usually confounded by ancient events, this suggests a much more dramatic decline than demographic data alone and emphasises the need for major conservation efforts.

  13. Asymmetric core collapse of rapidly rotating massive star

    Science.gov (United States)

    Gilkis, Avishai

    2018-02-01

    Non-axisymmetric features are found in the core collapse of a rapidly rotating massive star, which might have important implications for magnetic field amplification and production of a bipolar outflow that can explode the star, as well as for r-process nucleosynthesis and natal kicks. The collapse of an evolved rapidly rotating MZAMS = 54 M⊙ star is followed in three-dimensional hydrodynamic simulations using the FLASH code with neutrino leakage. A rotating proto-neutron star (PNS) forms with a non-zero linear velocity. This can contribute to the natal kick of the remnant compact object. The PNS is surrounded by a turbulent medium, where high shearing is likely to amplify magnetic fields, which in turn can drive a bipolar outflow. Neutron-rich material in the PNS vicinity might induce strong r-process nucleosynthesis. The rapidly rotating PNS possesses a rotational energy of E_rot ≳ 10^{52} erg. Magnetar formation proceeding in a similar fashion will be able to deposit a portion of this energy later on in the supernova ejecta through a spin-down mechanism. These processes can be important for rare supernovae generated by rapidly rotating progenitors, even though a complete explosion is not simulated in the present study.

  14. Varroa-virus interaction in collapsing honey bee colonies.

    Directory of Open Access Journals (Sweden)

    Roy M Francis

    Full Text Available Varroa mites and viruses are the currently the high-profile suspects in collapsing bee colonies. Therefore, seasonal variation in varroa load and viruses (Acute-Kashmir-Israeli complex (AKI and Deformed Wing Virus (DWV were monitored in a year-long study. We investigated the viral titres in honey bees and varroa mites from 23 colonies (15 apiaries under three treatment conditions: Organic acids (11 colonies, pyrethroid (9 colonies and untreated (3 colonies. Approximately 200 bees were sampled every month from April 2011 to October 2011, and April 2012. The 200 bees were split to 10 subsamples of 20 bees and analysed separately, which allows us to determine the prevalence of virus-infected bees. The treatment efficacy was often low for both treatments. In colonies where varroa treatment reduced the mite load, colonies overwintered successfully, allowing the mites and viruses to be carried over with the bees into the next season. In general, AKI and DWV titres did not show any notable response to the treatment and steadily increased over the season from April to October. In the untreated control group, titres increased most dramatically. Viral copies were correlated to number of varroa mites. Most colonies that collapsed over the winter had significantly higher AKI and DWV titres in October compared to survivors. Only treated colonies survived the winter. We discuss our results in relation to the varroa-virus model developed by Stephen Martin.

  15. Naked singularity explosion in higher-dimensional dust collapse

    CERN Document Server

    Shimano, Masahiro

    2013-01-01

    In the context of the large extra dimensions or TeV-scale gravity, it has been argued that an effective naked singularity, called the visible border of spacetime, would be generated by high-energy particle collisions. Motivated by this interesting possibility, we investigate a particle creation by a naked singularity in general dimensions, adopting a spherically symmetric self-similar dust collapse as the simple model of a naked singularity formation. The power and energy of the particle emission behave in two distinct ways depending on a parameter in the model. In a generic case, the emission power is proportional to the quadratic inverse of the remaining time to the Cauchy horizon, which has been known for the four-dimensional case in the literature. On the other hand, in a degenerate case the emission power is proportional to the quartic inverse of the remaining time to the Cauchy horizon, and depends on the total mass of a dust fluid in spite that the central region of the collapse is scale-free due to th...

  16. Gravitational collapse of rotating supermassive stars including nuclear burning effects

    Science.gov (United States)

    Uchida, Haruki; Shibata, Masaru; Yoshida, Takashi; Sekiguchi, Yuichiro; Umeda, Hideyuki

    2017-10-01

    Supermassive stars (SMSs) of mass ≳105 M⊙ are candidates for seeds of supermassive black holes found in the center of many massive galaxies. We simulate the gravitational collapse of a rigidly rotating SMS core including nuclear burning effects in axisymmetric numerical relativity. We consider SMS cores composed of primordial metallicity and of helium in this paper. We find that for our chosen initial conditions, the nuclear burning does not play an important role. After the collapse, a torus surrounding a rotating black hole is formed and a fraction of the torus material is ejected by a hydrodynamical effect. We quantitatively study the relation between the properties of these objects and rotation. We find that if a SMS core is sufficiently rapidly rotating, the rest mass of the torus and outflow are approximately 6% and 1% of the initial rest mass, respectively. The typical average velocity and the total kinetic energy of the outflow are 0.2 c and 1 054 -56 erg where c is the speed of light. Finally, we briefly discuss the possibility for observing the outflow, ringdown gravitational waves associated with the formation of black holes, and gravitational waves from the torus.

  17. Hydrophobic collapse of trigger factor monomer in solution.

    Directory of Open Access Journals (Sweden)

    Kushagra Singhal

    Full Text Available Trigger factor (TF is a chaperone, found in bacterial cells and chloroplasts, that interacts with nascent polypeptide chains to suppress aggregation. While its crystal structure has been resolved, the solution structure and dynamics are largely unknown. We performed multiple molecular dynamics simulations on Trigger factor in solution, and show that its tertiary domains display collective motions hinged about inter-domain linkers with minimal or no loss in secondary structure. Moreover, we find that isolated TF typically adopts a collapsed state, with the formation of domain pairs. This collapse of TF in solution is induced by hydrophobic interactions and stabilised by hydrophilic contacts. To determine the nature of the domain interactions, we analysed the hydrophobicity of the domain surfaces by using the hydrophobic probe method of Acharya et al., as the standard hydrophobicity scales predictions are limited due to the complex environment. We find that the formation of domain pairs changes the hydrophobic map of TF, making the N-terminal and arm2 domain pair more hydrophilic and the head and arm1 domain pair more hydrophobic. These insights into the dynamics and interactions of the TF domains are important to eventually understand chaperone-substrate interactions and chaperone function.

  18. The Final Stage of Gravitationally Collapsed Thick Matter Layers

    Directory of Open Access Journals (Sweden)

    Piero Nicolini

    2013-01-01

    Full Text Available In the presence of a minimal length, physical objects cannot collapse to an infinite density, singular, matter point. In this paper, we consider the possible final stage of the gravitational collapse of “thick” matter layers. The energy momentum tensor we choose to model these shell-like objects is a proper modification of the source for “noncommutative geometry inspired,” regular black holes. By using higher momenta of Gaussian distribution to localize matter at finite distance from the origin, we obtain new solutions of the Einstein equation which smoothly interpolates between Minkowski’s geometry near the center of the shell and Schwarzschild’s spacetime far away from the matter layer. The metric is curvature singularity free. Black hole type solutions exist only for “heavy” shells; that is, M ≥Me, where Me is the mass of the extremal configuration. We determine the Hawking temperature and a modified area law taking into account the extended nature of the source.

  19. Collapse of an ecological network in Ancient Egypt.

    Science.gov (United States)

    Yeakel, Justin D; Pires, Mathias M; Rudolf, Lars; Dominy, Nathaniel J; Koch, Paul L; Guimarães, Paulo R; Gross, Thilo

    2014-10-07

    The dynamics of ecosystem collapse are fundamental to determining how and why biological communities change through time, as well as the potential effects of extinctions on ecosystems. Here, we integrate depictions of mammals from Egyptian antiquity with direct lines of paleontological and archeological evidence to infer local extinctions and community dynamics over a 6,000-y span. The unprecedented temporal resolution of this dataset enables examination of how the tandem effects of human population growth and climate change can disrupt mammalian communities. We show that the extinctions of mammals in Egypt were nonrandom and that destabilizing changes in community composition coincided with abrupt aridification events and the attendant collapses of some complex societies. We also show that the roles of species in a community can change over time and that persistence is predicted by measures of species sensitivity, a function of local dynamic stability. To our knowledge, our study is the first high-resolution analysis of the ecological impacts of environmental change on predator-prey networks over millennial timescales and sheds light on the historical events that have shaped modern animal communities.

  20. The wavefunction of the collapsing Bose–Einstein condensate

    Science.gov (United States)

    Theodorakis, Stavros; Hadjigeorgiou, Andreas

    2017-12-01

    Bose–Einstein condensates with tunable interatomic interactions have been studied intensely in recent experiments. The investigation of the collapse of a condensate following a sudden change in the nature of the interaction from repulsive to attractive has led to the observation of a remnant condensate that did not undergo further collapse. We suggest that this high-density remnant is in fact the absolute minimum of the energy, if the attractive atomic interactions are nonlocal, and is therefore inherently stable. We show that a variational trial function consisting of a superposition of two distinct gaussians is an accurate representation of the wavefunction of the ground state of the conventional local Gross–Pitaevskii field equation for an attractive condensate and gives correctly the points of emergence of instability. We then use such a superposition of two gaussians as a variational trial function in order to calculate the minima of the energy when it includes a nonlocal interaction term. We use experimental data in order to study the long range of the nonlocal interaction, showing that they agree very well with a dimensionally derived expression for this range.

  1. COMMUNISM AND THE TRAUMA OF ITS COLLAPSE REVISITED.

    Science.gov (United States)

    Schmidt-Löw-Beer, Catherine; Atria, Moira; Davar, Elisha

    2015-12-01

    This paper focuses on the intertwinement of society and the psyche as a consequence of 70 years of Communist rule and the trauma of its collapse in the 90's. The trauma had profound effects on the psyche. An empirical study that was carried out in 1996/1997, which compared the personality structure of adolescents from Russia and Austria, and a research dialogue in 1999, has been re-evaluated in the light of current political events. One aim that we had was to find out whether we could discover characteristic personality features, resulting from the Communist totalitarian society in Russia, as well as from the trauma of its collapse. This led to the development of the concepts of the "impersonal self" and the "denial mode". The Russians seemed to be frozen in a protective shell with "flat" affects. They were anxious, conflict avoidant, and somewhat lost. Ideas about missing adolescence and the importance of privacy are discussed. Society was shown to not only have intruded into the individual psyche, but also into the members of the intercultural research team in the form of projective identification. The importance of the interaction between society and the individual as a basic psychoanalytic concept dating back to Freud is elaborated. Finally, considerations pertaining to mental health and democracy are presented.

  2. Where Does the Physics of Extreme Gravitational Collapse Reside?

    Directory of Open Access Journals (Sweden)

    Carlos Barceló

    2016-05-01

    Full Text Available The gravitational collapse of massive stars serves to manifest the most severe deviations of general relativity with respect to Newtonian gravity: the formation of horizons and spacetime singularities. Both features have proven to be catalysts of deep physical developments, especially when combined with the principles of quantum mechanics. Nonetheless, it is seldom remarked that it is hardly possible to combine all these developments into a unified theoretical model, while maintaining reasonable prospects for the independent experimental corroboration of its different parts. In this paper we review the current theoretical understanding of the physics of gravitational collapse in order to highlight this tension, stating the position that the standard view on evaporating black holes stands for. This serves as the motivation for the discussion of a recent proposal that offers the opposite perspective, represented by a set of geometries that regularize the classical singular behavior and present modifications of the near-horizon Schwarzschild geometry as the result of the propagation of non-perturbative ultraviolet effects originated in regions of high curvature. We present an extensive exploration of the necessary steps on the explicit construction of these geometries, and discuss how this proposal could change our present understanding of astrophysical black holes and even offer the possibility of detecting genuine ultraviolet effects in gravitational-wave experiments.

  3. In vitro susceptibility of goat mononuclear cells to bluetongue virus.

    Science.gov (United States)

    Garg, A K; Prasad, G

    1996-08-01

    Goat peripheral blood mononuclear cells were cultured and their susceptibility to bluetongue virus (BTV) serotype 1 was tested. A small number of adherent and non-adherent cells were found positive for BTV antigens by immunoperoxidase and immunofluorescence tests. Both adherent and non-adherent cells supported limited level of viral replication as evidenced by low titre in the biological assay, thus indicating their susceptibility.

  4. pso.ATION AND ANTIMICROBIAL SUSCEPTIBILITY

    African Journals Online (AJOL)

    isolates vere made using standard methods, Antibiotic susceptibility tests against commonly prescribed ... Acute otitis media is rapid with short .... sensitivity tests. Antimicrobial susceptibility tests: The antimicrobial susceptibility patterns of major Gram positive and negative bacterial isolates obtained from clinical specimens.

  5. Photometric Identification of Population III Core-Collapse Supernovae: Multicolor Light Curve Simulations

    Science.gov (United States)

    Tolstov, Alexey; Nomoto, Ken'ichi; Tominaga, Nozomu; Ishigaki, Miho N.; Blinnikov, Sergey; Suzuki, Tomoharu

    We study the multicolor light curves for a number of metal-free core-collapse supernova (SN) models (25-100 ⊙ ) to determine the indicators for the detection and identification of first generation SNe. We use mixing-fallback supernova explosion models that explain the observed abundance patterns of metal-poor stars. Numerical calculations of the multicolor light curves are performed using the multigroup radiation hydrodynamic code STELLA. The calculated light curves of metal-free SNe are compared with solar-metallicity models and observed SNe. We conclude that the multicolor light curves could be used to identify first-generation SNe in current (Subaru/HSC) and future transient surveys (LSST, James Webb Space Telescope). They are also suitable for identifying low-metallicity SNe in the nearby universe (PTF, Pan-STARRS, Gaia).

  6. High Structural Stability of Textile Implants Prevents Pore Collapse and Preserves Effective Porosity at Strain

    Directory of Open Access Journals (Sweden)

    Uwe Klinge

    2015-01-01

    Full Text Available Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS, which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.”

  7. UV-Vis Action Spectroscopy Reveals a Conformational Collapse in Hydrogen-Rich Dinucleotide Cation Radicals.

    Science.gov (United States)

    Korn, Joseph A; Urban, Jan; Dang, Andy; Nguyen, Huong T H; Tureček, František

    2017-09-07

    We report the generation of deoxyriboadenosine dinucleotide cation radicals by gas-phase electron transfer to dinucleotide dications and their noncovalent complexes with crown ether ligands. Stable dinucleotide cation radicals of a novel hydrogen-rich type were generated and characterized by tandem mass spectrometry and UV-vis photodissociation (UVPD) action spectroscopy. Electron structure theory analysis indicated that upon electron attachment the dinucleotide dications underwent a conformational collapse followed by intramolecular proton migrations between the nucleobases to give species whose calculated UV-vis absorption spectra matched the UVPD action spectra. Hydrogen-rich cation radicals generated from chimeric riboadenosine 5'-diesters gave UVPD action spectra that pointed to novel zwitterionic structures consisting of aromatic π-electron anion radicals intercalated between stacked positively charged adenine rings. Analogies with DNA ionization are discussed.

  8. Formation of low-δ18O rhyolites after caldera collapse at Yellowstone, Wyoming, USA

    Science.gov (United States)

    Bindeman, Ilya N.; Valley, John W.

    2000-08-01

    We present a new model for the genesis of low-δ18O rhyolites of the Yellowstone caldera based on analyses of zircons and individual quartz phenocrysts. Low-δ18O rhyolites were erupted soon after the massive caldera-forming Lava Creek Tuff eruption (602 ka, ˜1000 km3) and contain xenocrysts of quartz and zircon inherited from precaldera rhyolites. These zircons are isotopically zoned and out of equilibrium with their host low-δ18O melts and quartz. Diffusion modeling predicts that magmatic disequilibria of oxygen isotopes persists for as much as tens of thousands of years following nearly total remelting of the hydrothermally altered igneous roots of the depressed cauldron, in which the alteration-resistant quartz and zircon initially retained their δ18O values. These results link melting to caldera collapse, rule out rapid or catastrophic magma meteoric water interaction, and indicate wholesale melting rather than assimilation or partial melting.

  9. Nitric oxide and coral bleaching: is peroxynitrite generation required for symbiosis collapse?

    Science.gov (United States)

    Hawkins, Thomas D; Davy, Simon K

    2013-09-01

    The temperature-induced collapse ('bleaching') of the coral-dinoflagellate symbiosis is hypothesised to result from symbiont oxidative stress and a subsequent host innate immune-like response. This includes the production of nitric oxide (NO), which is involved in numerous microbial symbioses. Much of NO's cytotoxicity has been attributed to its conversion, in the presence of superoxide (O2(-)), to highly reactive peroxynitrite (ONOO(-)). However, ONOO(-) generation has yet to be observed in either a lower invertebrate or an intracellular mutualism. Using confocal laser scanning microscopy with the fluorescent ONOO(-) indicator aminophenyl fluorescein (APF), we observed strong evidence that ONOO(-) is generated in symbiotic Aiptasia pulchella under conditions known to induce thermal bleaching. However, a role for ONOO(-) in bleaching remains unclear as treatment with a peroxynitrite scavenger had no significant effect on thermal bleaching. Therefore, while ONOO(-) may have a potential for cytotoxicity, in vivo levels of the compound may be insufficient to affect bleaching.

  10. Hypnotic susceptibility and dream characteristics.

    Science.gov (United States)

    Zamore, N; Barrett, D

    1989-11-01

    This study examined the relationship of hypnotic susceptibility to a variety of dream characteristics and types of dream content. A Dream Questionnaire was constructed synthesizing Gibson's dream inventory and Hilgard's theoretical conceptions of hypnosis. Employing the Harvard Group Scale of Hypnotic Susceptibility and the Field Inventory for evaluating hypnotic response, several dream dimensions correlated significantly with hypnotizability. For subjects as a whole, the strongest correlates were the frequency of dreams which they believed to be precognitive and out-of-body dreams. Ability to dream on a chosen topic also correlated significantly with hypnotic susceptibility for both genders. For females only, there was a negative correlation of hypnotic susceptibility to flying dreams. Absorption correlated positively with dream recall, ability to dream on a chosen topic, reports of conflict resolution in dreams, creative ideas occurring in dreams, amount of color in dreams, pleasantness of dreams, bizarreness of dreams, flying dreams and precognitive dreams.

  11. Risk factors of severe hand, foot and mouth disease complicated with cardiopulmonary collapse.

    Science.gov (United States)

    Song, Chunlan; Yibing, Cheng; Guo, Yanjun; Jin, Zhipeng; Cui, Yajie; Gu, Xue

    2015-07-01

    The aim of this study was to investigate the risk factors for severe hand, foot and mouth disease (HFMD) complicated with cardiopulmonary collapse in children. In total, 176 children aged 6-45 months with severe HFMD from March 2013 to May 2014 were enrolled in the study and divided into two groups, one with cardiopulmonary collapse and the other without. Univariate analysis and multiple logistic regression analysis were used to analyze the risk factors for severe HFMD complicated with cardiopulmonary collapse. The univariate analysis showed that there was no significant correlation between age, body temperature, consciousness disorders, blood glucose level and severe HFMD complicated with cardiopulmonary collapse. The multiple logistic regression analysis demonstrated that vomiting, circulatory disturbance, enterovirus 71 infection, dysfunction of respiratory rhythm and high level of brain natriuretic peptide were five independent risk factors for severe HFMD complicated with cardiopulmonary collapse. Children with HFMD and the above five risk factors may be at risk for cardiopulmonary collapse and poor prognosis.

  12. Quantum discord as a tool for comparing collapse models and decoherence

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Shreya, E-mail: shreya.banerjee@tifr.res.in; Bera, Sayantani, E-mail: sayantani.bera@tifr.res.in; Singh, Tejinder P., E-mail: tpsingh@tifr.res.in

    2016-11-25

    Highlights: • Collapse and decoherence models have been compared using quantum discord. • A macroscopic entanglement experimental set up has been used for this purpose. • Detection of the above effects with present experimental time not possible. • Bounds on the collapse parameters have been obtained from this analysis. - Abstract: The quantum to classical transition maybe caused by decoherence or by dynamical collapse of the wave-function. We propose quantum discord as a tool, (1) for comparing and contrasting the role of a collapse model (Continuous Spontaneous Localisation) and various sources of decoherence (environmental and fundamental), (2) for detecting collapse model and fundamental decoherence for an experimentally demonstrated macroscopic entanglement. We discuss the experimental times which will lead to the detection of either Continuous Spontaneous Localisation or fundamental decoherence. We further put bounds on the collapse parameters from this experiment for quantum discord.

  13. Ancestral susceptibility to colorectal cancer

    Czech Academy of Sciences Publication Activity Database

    Huhn, S.; Pardini, Barbara; Naccarati, Alessio; Vodička, Pavel (ed.); Hemminki, K.; Försti, A.

    2012-01-01

    Roč. 27, č. 2 (2012), s. 197-204 ISSN 0267-8357 R&D Projects: GA ČR GA310/07/1430; GA ČR GAP304/10/1286 Grant - others:EU FP7(XE) HEALTH-F4-2007-200767 Institutional research plan: CEZ:AV0Z50390512 Keywords : cancer susceptibility * molecular epidemiology * genetic susceptibility Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.500, year: 2012

  14. Delayed Post-traumatic Vertebral Collapse: MR Categorization and MR-Pathology Correlation

    OpenAIRE

    Lee, Chong Suh; Yu, Je-Wook; Chung, Sung Soo; Suh, Yeon-Lim; Ahn, Geunghwan; Ahn, Joong Mo

    2007-01-01

    Study Design A retrospective study. Purpose To categorize the MR appearance of ischemic vertebral collapse and to correlate surgical and histologic findings. Overview of Literature X-ray and MRI findings of delayed posttraumatic vertebral collapse shows several patterns. Histopathologic signs of osteonecrosis were present only in minor portion of cases sampled for biopsy of delayed post-traumatic vertebral collapse in the literature. Methods Twenty-one patients (22 vertebral bodies), with sur...

  15. Collapse and recovery of forage fish populations prior to commercial exploitation

    Science.gov (United States)

    McClatchie, S.; Hendy, I. L.; Thompson, A. R.; Watson, W.

    2017-02-01

    We use a new, well-calibrated 500 year paleorecord off southern California to determine collapse frequency, cross correlation, persistence, and return times of exploited forage fish populations. The paleorecord shows that "collapse" (defined as forage. Forage populations are resilient on the 500 year time scale, but their collapse and recovery cycle (based on the paleorecord) are suited to alternating periods of high fishing mortality and periods of little or no fishing.

  16. Radiative gravitational collapse to spherical, toroidal and higher genus black holes

    Science.gov (United States)

    Mena, Filipe C.; Oliveira, João M.

    2017-12-01

    We derive the matching conditions between FLRW and generalised Vaidya spacetimes with spherical, planar or hyperbolic symmetry, across timelike hypersurfaces. We then construct new models of gravitational collapse of FLRW spacetimes with a negative cosmological constant having electromagnetic radiation in the exterior. The final state of the collapse are asymptotically AdS black holes with spherical, toroidal or higher genus topologies. We analyse the collapse dynamics including trapped surface formation, for various examples.

  17. The Wang-Meng interacting model and the gravitational collapse

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Miguel de [Universidade Federal de Roraima, Boa Vista (Brazil)

    2013-07-01

    collapse with a vacuum energy interacting with the collapsing matter content? Resuming, we study in this work the gravitational collapse of a star fluid that interacts with a vacuum energy component, via Wang-Meng approach. (author)

  18. Theoretical and experimental research on progressive collapse of RC frame buildings

    Directory of Open Access Journals (Sweden)

    Marin Lupoae

    2013-09-01

    Full Text Available Progressive collapse of the buildings has become an important issue to be studied in recent years due to the catastrophic nature of its effects. This subject can be approached from two different perspectives: one where an ideal collapse of the structure is aimed to be achieved and corresponds to the controlled demolition of buildings and other which treats the mitigation of the potential of progressive collapse of structures. The paper presents the results of theoretical and experimental research conducted by the authors regarding the progressive collapse of RC structures from the two perspectives above mentioned.

  19. Characterizing 6 August 2007 Crandall Canyon mine collapse from ALOS PALSAR InSAR

    Science.gov (United States)

    Lu, Zhong; Wicks, Charles

    2010-01-01

    We used ALOS InSAR images to study land surface deformation over the Crandall Canyon mine in Utah, which collapsed on 6 August 2007 and killed six miners. The collapse was registered as a ML 3.9 seismic event. An InSAR image spanning the time of the collapse shows 25–30 cm surface subsidence over the mine. We used distributed dislocation sources to model the deformation field, and found that a collapse source model alone does not adequately fit the deformation

  20. Atomic Structure and Energy Distribution of Collapsed Carbon Nanotubes of Different Chiralities

    Directory of Open Access Journals (Sweden)

    Julia A. Baimova

    2015-01-01

    Full Text Available For carbon nanotubes of sufficiently large diameter at sufficiently low temperature, due to the action of the van der Waals forces, the ground state is a bilayer graphene with closed edges, the so-called collapsed configuration. Molecular dynamics simulation of collapsed carbon nanotubes is performed. The effect of length, diameter, and chirality of the nanotubes on their properties is investigated. It is shown that collapsed nanotubes after relaxation have rippled structure which is strongly dependent on the nanotube chirality. The structural properties are studied by calculating the radial distribution function and energy distribution along various regions in the collapsed carbon nanotubes.

  1. Susceptibility of lady beetles (Coleoptera: Coccinellidae) to entomopathogenic nematodes.

    Science.gov (United States)

    Shapiro-Ilan, David I; Cottrell, Ted E

    2005-06-01

    We investigated differential susceptibility of lady beetles to entomopathogenic nematodes, for two reasons: (1) to estimate potential nontarget effects on natural lady beetle populations, (2) to compare the susceptibility of exotic versus native lady beetle species. We hypothesize that successful establishment of some exotically introduced arthropods may be due, in part, to a lower susceptibility relative to competing native species. In laboratory studies, we compared the pathogenicity, virulence, and reproductive capacity of Heterorhabditis bacteriophora and Steinernema carpocapsae among two native (Coleomegilla maculata and Olla v-nigrum) and two successfully established exotic (Harmonia axyridis and Coccinella septempunctata) lady beetles, and a known susceptible lepidopteran host, Agrotis ipsilon. After 1 and 2 days of exposure to either nematode species, mortality of A. ipsilon was higher than in all lady beetles. Thus, we predict that nematode field applications would have significantly less impact on lady beetle populations than on a susceptible target pest. Additionally, the impact of soil-applied nematodes may be lower on lady beetles than on soil-dwelling hosts because the former spends relatively less time on the soil. Exotic lady beetles were less susceptible to nematode infection than native species. Reproductive capacity data also indicated lower host suitability in H. axyridis, but not in C. septempunctata. Overall, the hypothesis that low susceptibility to pathogens in certain exotic lady beetles may have contributed to competitive establishment was supported (especially for H. axyridis). Additional studies incorporating different hosts and pathogens from various geographic locations will be required to further address the hypothesis.

  2. Genetic heterogeneity in breast cancer susceptibility.

    Science.gov (United States)

    Andersen, T I

    1996-01-01

    Approximately 20% of breast cancer patients have a family history of the disease, and in one-fourth of these cases breast cancer appears to be inherited as an autosomally dominant trait. Five genes and gene regions involved in breast cancer susceptibility have been uncovered. Germ-line mutations in the recently cloned BRCA1 gene at 17q21 is considered to be responsible for the disease in a majority of the breast-ovarian cancer families and in 40-45% of the site-specific breast cancer families, but appears not to be involved in families with both male and female breast cancer cases. The BRCA2 locus at 13q12-q13 appears to be involved in 40-45% of the site-specific breast cancer families, and in most of the families with affected males. The gene located in this region, however, does not seem to confer susceptibility to ovarian cancer. The TP53 gene is involved in breast cancer development in the Li-Fraumeni syndrome and Li-Fraumeni syndrom-like families, whereas germ-line mutations in the androgen receptor (AR) gene is present in a subset of male breast cancers. Furthermore, females who are obligate carriers of ataxia telangiectasia (AT) have a 4-12 times relative risk of developing breast cancer as compared with the general female population, indicating that germ-line mutations in AT also confer susceptibility to breast cancer.

  3. Nuclear collapse observed during the eruption of Mt. Usu

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Taka-aki [Hokkaido Univ., Dept. of Nuclear Engineering, Sapporo, Hokkaido (Japan)

    2002-09-01

    Mt. Usu which was located about 70 km southwest from Sapporo in Hokkaido (the north island of Japan) began to erupt on March 31 in 2000. A nuclear emulsion was placed on a foot of Mt. Usu to catch small atomic clusters which were expected to be emitted during the eruption. Curious atomic clusters and their reaction products were successfully observed on surfaces of the nuclear emulsion. By comparing them with similar products which were obtained in previous experiments of discharge and electrolysis, it was concluded that micro Ball Lightning was really emitted during the eruption of Mt. Usu and that explosive reactions by nuclear collapse could have been involved to contribute to energy of the eruption. (author)

  4. Nuclear collapse observed during the eruption of Mt. Usu

    CERN Document Server

    Matsumoto, T A

    2002-01-01

    Mt. Usu which was located about 70 km southwest from Sapporo in Hokkaido (the north island of Japan) began to erupt on March 31 in 2000. A nuclear emulsion was placed on a foot of Mt. Usu to catch small atomic clusters which were expected to be emitted during the eruption. Curious atomic clusters and their reaction products were successfully observed on surfaces of the nuclear emulsion. By comparing them with similar products which were obtained in previous experiments of discharge and electrolysis, it was concluded that micro Ball Lightning was really emitted during the eruption of Mt. Usu and that explosive reactions by nuclear collapse could have been involved to contribute to energy of the eruption. (author)

  5. Core-collapse supernovae - successes, problems, and perspectives

    CERN Document Server

    Janka, H T

    2000-01-01

    Multi-dimensional hydrodynamic simulations of the post-bounce evolution of collapsed stellar iron cores have demonstrated that convective overturn between the stalled shock and the neutrinosphere can have an important effect on the neutrino-driven explosion mechanism. Whether a model yields a successful explosion or not, however, still depends on the power of neutrino energy deposition behind the stalled shock. The neutrino interaction with the stellar gas in the 'hot bubble' also determines the duration of the shock stagnation phase, the explosion energy, and the composition of the neutrino-heated supernova ejecta. More accurate models require a more precise calculation of the neutrino luminosities and spectra and of the angular distributions of the neutrinos in the heating region. Therefore it is necessary to improve the numerical treatment of the neutrino transport, to take into account convective processes inside the newly formed neutron star, and to develop a better understanding of the neutrino opacitie...

  6. Experimental approach on the collapse mechanism of CFRP composite tubes

    Science.gov (United States)

    Kim, Y. N.; Im, K. H.; Park, J. W.; Yang, I. Y.

    2001-04-01

    This study is to investigate the energy absorption characteristics of CFRP(Carbon-Fiber Reinforced Plastics) tubes on static and dynamic tests. Axial static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and dynamic compression tests have been utilized using an vertical crushing testing machine. When such tubes are subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that could control the crushing process. The collapse characteristics and energy absorption have been examined for various tubes. Energy absorption of the tubes are increased as changes in the lay-up which may increase the modulus of tubes. The results have been varied significantly as a function of ply orientation and interlaminar number. In general, the stacking sequence [0/90] CFRP tubes absorbed more energy than the [15/-15] CFRP tubes.

  7. Precursor Events Involving Plasmas Structures Around Collapsing Black Holes Binaries

    Science.gov (United States)

    Medvedev, M.; Coppi, B.

    2017-10-01

    The plasma structures that can exist around black hole binaries can sustain intrinsic plasma collective modes that have characteristic low frequencies related to the particle rotation frequencies around the binary system. As the collapse approaches, with the loss of angular momentum by emission of gravitational waves from the binary system we have suggested that the frequency of the fluctuating component of the gravitational potential can go through that of the intrinsic modes of the surrounding plasma structure and lead to a sharp amplification of them. Then the precursor to the event reported in Ref., tentatively identified by the Agile X- γ-ray observatory may be associated with the high energy radiation emission due to the fields produced by excitation of the proposed plasma modes. M. Tavani is thanked for bringing Ref. to our attention while Ref. was being completed. Sponsored in part by the U.S. DoE.

  8. Factors Predicting Late Collapse of Distal Radius Fractures

    Directory of Open Access Journals (Sweden)

    Neritan Myderrizi

    2011-11-01

    Full Text Available BACKGROUND: Although fractures of the distal radius are a common clinical presentation, many factors affect instability of these injuries. The aim of this study was to assess the influence of age, sex, distal radial ulnar joint injury (DRUJ, ulnar styloid fracture, and dorsal displacement in late collapse of distal radius fractures. METHODS: Three hundred twenty-nine patient fractures were measured for dorsal tilt, radial inclination and ulnar variance after reduction and 2 months later. Reduction loss was analysed statistically against variables like DRUJ involvement, ulnar styloid fractures, age, sex, and AO classification. RESULTS: After two months there was loss of reduction in 171(51.9% cases. Loss of reduction was related to age, AO classification, involvement of DRUJ, ulnar styloid fractures and initial displacement. CONCLUSION: Factors such as age, associated DRUJ injury, ulnar styloid fracture are predictive of loss of reduction. Knowing these predictor factors, can aid in decision regarding treatment methods.

  9. Uncertainty in Explosive Yields of Core-Collapse Supernovae

    Science.gov (United States)

    Andrews, Sydney; Fryer, Chris; Even, Wesley P.; Jones, Samuel; Pignatari, Marco; NuGrid Collaboration

    2017-01-01

    The chemical composition of the ejecta from the violent explosions of massive stars has been vital for probing the nature of the explosions and their effect on galactic chemical evolution and universal chemical composition. The sensitivity of numerical explosive nucleosynthetic yields in core-collapse supernovae to several key parameters is examined in one dimension. This uncertainty study is applied to 15, 20, and 25 solar mass stars with different energy prescriptions for shock revival. The effects of the resolution of the temperature and density profiles run through the NuGrid nuclear network are explored, as well as the differences between large and small isotope networks for the initial conditions of the explosion calculations.

  10. Climate Change and Market Collapse: A Model Applied to Darfur

    Directory of Open Access Journals (Sweden)

    Ola Olsson

    2016-03-01

    Full Text Available A recurring argument in the global debate is that climate deterioration is likely to make social conflicts over diminishing natural resources more common in the future. The exact mechanism behind such a development has so far not been successfully characterized in the literature. In this paper, we present a general model of a community populated by farmers and herders who can either divide up land in a market economy or in autarky. The key insight from our model is that decreasing resources can make trade between the two groups collapse, which in turn makes each group’s welfare independent of that of the other. Predictions from the model are then applied to the conflict in Darfur. Our analysis suggests that three decades of drought in the area can at least partially explain the observed disintegration of markets and the subsequent rise of social tensions.

  11. Supermassive black holes formed by direct collapse of inflationary perturbations

    CERN Document Server

    Nakama, Tomohiro; Yokoyama, Jun'ichi

    2016-01-01

    We propose a mechanism of producing a new type of primordial perturbations which collapse to primordial black holes whose mass can be as large as necessary for them to grow to the supermassive black holes observed at high redshifts, without contradicting COBE/FIRAS upper limits on cosmic microwave background (CMB) spectral distortions. In our model, the observable Universe consists of two kinds of many small patches which experienced different expansion histories during inflation. Large amplitudes of primordial perturbations enough to form primordial black holes are realized on patches that experienced more Hubble expansion than the others. By making these patches the minor component, the rarity of supermassive black holes can be explained. On the other hand, most regions of the Universe experienced the standard history and hence have only standard almost scale-invariant adiabatic perturbations confirmed by observations of CMB or large-scale structures of the universe. Thus our mechanism can evade the constra...

  12. Technical note: measurement of collapse cavitation in ultrasound fields.

    Science.gov (United States)

    Digby, M; Duck, F A; Lenz, E J; Price, G J

    1995-11-01

    This note describes a method for the measurement of hydroxyl free radical concentration due to collapse acoustic cavitation in medical ultrasound fields using aqueous terephthalic acid (TA) solution. An enclosed cylindrical chamber with acoustically transparent membranes at either end was used. Control of cavitation activity was achieved by seeding the solution with polystyrene microspheres to provide cavitation centres. Insonation experiments using unseeded TA previously exposed to air gave very variable results, sometimes detecting cavitation activity and at other times detecting nothing, under the same exposure conditions. Introduction of polystyrene microsphere seeds into the TA enabled it to detect reproducibly levels of cavitation activity at least one order of magnitude higher than in unseeded solutions. An experiment using the seeded TA in a standing wave ultrasound field, set up using a brass reflecting plate, demonstrated that the presence of a standing wave inhibited the measured cavitation yield.

  13. Prompt merger collapse and the maximum mass of neutron stars.

    Science.gov (United States)

    Bauswein, A; Baumgarte, T W; Janka, H-T

    2013-09-27

    We perform hydrodynamical simulations of neutron-star mergers for a large sample of temperature-dependent nuclear equations of state and determine the threshold mass above which the merger remnant promptly collapses to form a black hole. We find that, depending on the equation of state, the threshold mass is larger than the maximum mass of a nonrotating star in isolation by between 30 and 70 percent. Our simulations also show that the ratio between the threshold mass and maximum mass is tightly correlated with the compactness of the nonrotating maximum-mass configuration. We speculate on how this relation can be used to derive constraints on neutron-star properties from future observations.

  14. Cod Collapse and the Climate in the North Atlantic

    Science.gov (United States)

    Meng, K. C.; Oremus, K. L.; Gaines, S.

    2014-12-01

    Effective fisheries management requires forecasting population changes. We find a negative relationship between the North Atlantic Oscillation (NAO) index and subsequently surveyed biomass and catch of Atlantic cod, Gadus morhua, off the New England coast. A 1-unit NAO increase is associated with a 17% decrease in surveyed biomass of age-1 cod the following year. This relationship persists as the cod mature, such that observed NAO can be used to forecast future adult biomass. We also document that an NAO event lowers catch for up to 15 years afterward. In contrast to forecasts by existing stock assessment models, our NAO-driven statistical model successfully hindcasts the recent collapse of New England cod fisheries following strong NAO events in 2007 and 2008 (see figure). This finding can serve as a template for forecasting other fisheries affected by climatic conditions.

  15. On Unitary Evolution and Collapse in Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Francesco Giacosa

    2014-11-01

    Full Text Available In the framework of an interference setup in which only two outcomes are possible (such as in the case of a Mach–Zehnder interferometer, we discuss in a simple and pedagogical way the difference between a standard, unitary quantum mechanical evolution and the existence of a real collapse of the wavefunction. This is a central and not-yet resolved question of quantum mechanics and indeed of quantum field theory as well. Moreover, we also present the Elitzur–Vaidman bomb, the delayed choice experiment, and the effect of decoherence. In the end, we propose two simple experiments to visualize decoherence and to test the role of an entangled particle.Quanta 2014; 3: 156–170.

  16. The Height Distribution of Core Collapse Supernovae in Disk Galaxies

    Science.gov (United States)

    Molloy, M.; Meurs, E.; Norci, L.; Kavanagh, P.

    Core collapse (CC) supernovae are exploding massive stars and are therefore expected to occur in the disks of spiral galaxies. However, in the historical record some CC SNae can be noticed outside the disks. To investigate this further, the distribution of SNae above and below the disks of spiral galaxies is examined for the case of edge-on galaxies. The CC SNae that are observed away from their parent Population I in the galaxy planes must previously have left the disks due to dynamical encounters or SN explosions of companion stars. We develop a simple interpretative model that describes the observed height distribution of the SNae, taking into account kick velocities imparted during the explosive events. We also briefly comment on the radial distribution of SNae, utilizing face-on galaxies for this purpose.

  17. Evaluation and treatment of trauma related collapse in athletes.

    Science.gov (United States)

    Gammons, Matthew

    2014-12-01

    Although blunt traumatic injuries are common in athletes, life-threatening trauma is fortunately rare. Most current literature has focused on nontraumatic causes of athlete death though traumatic injuries may be more common. Although prevention of these injuries may be more difficult than nontraumatic causes, prompt recognition and treatment is paramount. Common traumatic causes of collapse athlete generally involve the head, neck, and trunk and are more frequent in collision sports. Other higher risk sports include track and field, cheerleading, snow sports, and those involving motorized vehicles. Health care providers who participate in sports coverage should be aware of the potential for these injuries as emergency treatment is required to maximize outcomes. Emergency action plans allow providers to expediently activate emergency management services while providing treatment and stabilization.

  18. The two promising scenarios to explode core collapse supernovae

    Science.gov (United States)

    Soker, Noam

    2017-10-01

    I compare to each other what I consider to be the two most promising scenarios to explode core-collapse supernovae (CCSNe). Both are based on the negative jet feedback mechanism (JFM). In the jittering jets scenario a collapsing core of a single slowly-rotating star can launch jets. The accretion disk or belt (a sub-Keplerian accretion flow concentrated toward the equatorial plane) that launches the jets is intermittent with varying directions of the axis. Instabilities, such as the standing accretion shock instability (SASI), lead to stochastic angular momentum variations that allow the formation of the intermittent accretion disks/belts. According to this scenario no failed CCSNe exist. According to the fixed axis scenario, the core of the progenitor star must be spun up during its late evolutionary phases, and hence all CCSNe are descendants of strongly interacting binary systems, most likely through a common envelope evolution (whether the companion survives or not). Due to the strong binary interaction, the axis of the accretion disk that is formed around the newly born neutron star has a more or less fixed direction. According to the fixed axis scenario, accretion disks/belts are not formed around the newly born neutron star of single stars; they rather end in failed CCSNe. I also raise the possibility that the jittering jets scenario operates for progenitors with initial mass of 8 {M}ȯ ≲ {M}{ZAMS}≲ 18 {M}ȯ , while the fixed axis scenario operates for {M}{ZAMS}≳ 18 {M}ȯ . For the first time these two scenarios are compared to each other, as well as to some aspects of the neutrino-driven explosion mechanism. These new comparisons further suggest that the JFM plays a major role in exploding massive stars.

  19. Macro-ions collapse leading to hybrid bio-nanomaterials.

    Energy Technology Data Exchange (ETDEWEB)

    Achyuthan, Komandoor E.

    2009-10-01

    I used supramolecular self-assembling cyanine and the polyamine spermine binding to Escherichia coli genomic DNA as a model for DNA collapse during high throughput screening. Polyamine binding to DNA converts the normally right handed B-DNA into left handed Z-DNA conformation. Polyamine binding to DNA was inhibited by the supramolecular self-assembling cyanine. Self-assembly of cyanine upon DNA scaffold was likewise competitively inhibited by spermine as signaled by fluorescence quench from DNA-cyanine ensemble. Sequence of DNA exposure to cyanine or spermine was critical in determining the magnitude of fluorescence quench. Methanol potentiated spermine inhibition by >10-fold. The IC{sub 50} for spermine inhibition was 0.35 {+-} 0.03 {micro}M and the association constant Ka was 2.86 x 10{sup -6}M. Reversibility of the DNA-polyamine interactions was evident from quench mitigation at higher concentrations of cyanine. System flexibility was demonstrated by similar spermine interactions with {lambda}DNA. The choices and rationale regarding the polyamine, the cyanine dye as well as the remarkable effects of methanol are discussed in detail. Cyanine might be a safer alternative to the mutagenic toxin ethidium bromide for investigating DNA-drug interactions. The combined actions of polyamines and alcohols mediate DNA collapse producing hybrid bio-nanomaterials with novel signaling properties that might be useful in biosensor applications. Finally, this work will be submitted to Analytical Sciences (Japan) for publication. This journal published our earlier, related work on cyanine supramolecular self-assembly upon a variety of nucleic acid scaffolds.

  20. Spherical collapse of dark energy with an arbitrary sound speed

    Energy Technology Data Exchange (ETDEWEB)

    Basse, Tobias; Bjælde, Ole Eggers [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Wong, Yvonne Y.Y., E-mail: tb06@phys.au.dk, E-mail: oeb@phys.au.dk, E-mail: yvonne.wong@physik.rwth-aachen.de [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen, D-52056 Aachen (Germany)

    2011-10-01

    We consider a generic type of dark energy fluid, characterised by a constant equation of state parameter w and sound speed c{sub s}, and investigate the impact of dark energy clustering on cosmic structure formation using the spherical collapse model. Along the way, we also discuss in detail the evolution of dark energy perturbations in the linear regime. We find that the introduction of a finite sound speed into the picture necessarily induces a scale-dependence in the dark energy clustering, which in turn affects the dynamics of the spherical collapse in a scale-dependent way. As with other, more conventional fluids, we can define a Jeans scale for the dark energy clustering, and hence a Jeans mass M{sub J} for the dark matter which feels the effect of dark energy clustering via gravitational interactions. For bound objects (halos) with masses M >> M{sub J}, the effect of dark energy clustering is maximal. For those with M << M{sub J}, the dark energy component is effectively homogeneous, and its role in the formation of these structures is reduced to its effects on the Hubble expansion rate. To compute quantitatively the virial density and the linearly extrapolated threshold density, we use a quasi-linear approach which is expected to be valid up to around the Jeans mass. We find an interesting dependence of these quantities on the halo mass M, given some w and c{sub s}. The dependence is the strongest for masses lying in the vicinity of M ∼ M{sub J}. Observing this M-dependence will be a tell-tale sign that dark energy is dynamic, and a great leap towards pinning down its clustering properties.

  1. The direct identification of core-collapse supernova progenitors

    Science.gov (United States)

    Van Dyk, Schuyler D.

    2017-09-01

    To place core-collapse supernovae (SNe) in context with the evolution of massive stars, it is necessary to determine their stellar origins. I describe the direct identification of SN progenitors in existing pre-explosion images, particularly those obtained through serendipitous imaging of nearby galaxies by the Hubble Space Telescope. I comment on specific cases representing the various core-collapse SN types. Establishing the astrometric coincidence of a SN with its putative progenitor is relatively straightforward. One merely needs a comparably high-resolution image of the SN itself and its stellar environment to perform this matching. The interpretation of these results, though, is far more complicated and fraught with larger uncertainties, including assumptions of the distance to and the extinction of the SN, as well as the metallicity of the SN environment. Furthermore, existing theoretical stellar evolutionary tracks exhibit significant variations one from the next. Nonetheless, it appears fairly certain that Type II-P (plateau) SNe arise from massive stars in the red supergiant phase. Many of the known cases are associated with subluminous Type II-P events. The progenitors of Type II-L (linear) SNe are less established. Among the stripped-envelope SNe, there are now a number of examples of cool, but not red, supergiants (presumably in binaries) as Type IIb progenitors. We appear now finally to have an identified progenitor of a Type Ib SN, but no known example yet for a Type Ic. The connection has been made between some Type IIn SNe and progenitor stars in a luminous blue variable phase, but that link is still thin, based on direct identifications. Finally, I also describe the need to revisit the SN site, long after the SN has faded, to confirm the progenitor identification through the star's disappearance and potentially to detect a putative binary companion that may have survived the explosion. This article is part of the themed issue 'Bridging the gap

  2. Upper airway collapsibility and genioglossus activity in adolescents during sleep.

    Science.gov (United States)

    Huang, Jingtao; Pinto, Swaroop J; Yuan, Haibo; Katz, Eliot S; Karamessinis, Laurie R; Bradford, Ruth M; Gallagher, Paul R; Hannigan, James T; Nixon, Thomas; Ward, Michelle B; Lee, Yin N; Marcus, Carole L

    2012-10-01

    Obese patients develop obstructive sleep apnea syndrome (OSAS), at least in part because of a narrowed upper airway. However, many obese adolescents do not develop OSAS, despite having a presumably narrower airway. The reasons for this phenomenon are unclear. The authors hypothesized that obese controls have a compensatory neuromuscular response to subatmospheric pressure loads during sleep, making them less likely to develop upper airway collapse. Patients underwent pressure-flow measurements during sleep while wearing intraoral electrodes to measure genioglossal electromyography (EMGgg). Two techniques were applied to decrease nasal pressure (P(N)) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway. Sleep laboratory. There were 35 obese patients with OSAS, 28 obese controls, and 43 lean controls. In the activated state, the two control groups had a flatter slope of the pressure-flow relationship and a more negative critical closing pressure (less collapsible) than the OSAS group. In the hypotonic state, the lean controls had a flatter slope of the pressure-flow relationship than the OSAS and obese control groups. In the activated state, the slope of EMGgg versus P(N) was greater in the obese control group than in the OSAS or lean control groups (P = 0.002 and P = 0.028, respectively); there were no differences in the hypotonic state. Obese controls have vigorous upper airway neuromuscular responses during sleep. Upper airway reflexes normally decline during adolescent development. It is speculated that obese adolescents without OSAS maintain protective upper airway reflexes during adolescent development, whereas those who go on to develop OSAS do not.

  3. Wavefunction Collapse via a Nonlocal Relativistic Variational Principle

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Alan K. [Los Alamos National Laboratory

    2012-06-18

    Since the origin of quantum theory in the 1920's, some of its practitioners (and founders) have been troubled by some of its features, including indeterminacy, nonlocality and entanglement. The 'collapse' process described in the Copenhagen Interpretation is suspect for several reasons, and the act of 'measurement,' which is supposed to delimit its regime of validity, has never been unambiguously defined. In recent decades, nonlocality and entanglement have been studied energetically, both theoretically and experimentally, and the theory has been reinterpreted in imaginative ways, but many mysteries remain. We propose that it is necessary to replace the theory by one that is explicitly nonlinear and nonlocal, and does not distinguish between measurement and non-measurement regimes. We have constructed such a theory, for which the phase of the wavefunction plays the role of a hidden variable via the process of zitterbewegung. To capture this effect, the theory must be relativistic, even when describing nonrelativistic phenomena. It is formulated as a variational principle, in which Nature attempts to minimize the sum of two spacetime integrals. The first integral tends to drive the solution toward a solution of the standard quantum mechanical wave equation, and also enforces the Born rule of outcome probabilities. The second integral drives the collapse process. We demonstrate that the new theory correctly predicts the possible outcomes of the electron two-slit experiment, including the infamous 'delayed-choice' variant. We observe that it appears to resolve some long-standing mysteries, but introduces new ones, including possible retrocausality (a cause later than its effect). It is not clear whether the new theory is deterministic.

  4. Collapsing Glomerulopathy: A Single Centre Clinicopathologic Study of Seven Years.

    Science.gov (United States)

    Kanodia, Kamal V; Vanikar, Aruna V; Patel, Rashmi D; Suthar, Kamlesh S; Nigam, Lovelesh K; Patel, Himanshu V; Kute, Vivek; Trivedi, Hargovind L

    2016-04-01

    Collapsing Glomerulopathy (CG) is recognized as distinct pattern of proliferative parenchymal injury with poor response to empirical therapy. A single center retrospective study was carried out to find out clinicopathological features of idiopathic CG. A total of 3335 native renal biopsies were analyzed retrospectively which were performed from 2008 to 2014 with emphasis on clinicopathological correlation and histopathological presentation. Idiopathic CG constituted 0.75% incidence (25 out of 3335 biopsies) of all biopsies, adults constituting major study part with 88%. The duration of the symptoms at the time of biopsy was 34.12±26.09 days and 35±22.91 days respectively in adults and children. Hypertension was noted in 9(40.9%) and oliguria in 8(36.4%) in adults. Urinalysis revealed microscopic haematuria 12(54.5%) in adults. Nephrotic range proteinuria was reported in 10 (45.5%) adult patients. Glomerular collapse with hyperplasia/ hypertrophy of podocytes was seen in 4.54±3.11 glomeruli. Tubular microcystic dilation was seen in 16(64%) patients. Tubular atrophy involving mild (t1) in 15(60%), moderate (t2) in 4(16%) and severe (t3) in 6(24%) patients. Interstitial fibrosis was mild (i1) in 17(68%), moderate (i2) in 2(8%) and severe (i3) in 6(24%) patients. Idiopathic CG is a morphological pattern of grave podocyte injury with poor prognosis. However, there are chances of remission/ recovery if the tubular atrophy and interstitial fibrosis are of grades ≤ t1 i1.

  5. Origin of calderas: discriminating between collapses and explosions

    Directory of Open Access Journals (Sweden)

    Izumi Yokoyama

    2017-01-01

    Full Text Available Origins of calderas may differ according to their subsurface structure that may be characterized by high or low density deposits that may be observed as high or low gravity anomalies, respectively. In the Introduction, the pioneering work of Fouqué[1879] on Santorini caldera is referred to in relation to definition of calderas. First, our discussion is focused on four calderas that were seen forming during the period from 1815 (the Tambora eruption to 1991 (the Pinatubo eruption. Coincidently, these four calderas are all low-gravity-anomaly type. Their formation processes and subsurface structure are summarized by the existing data analyzed by various authors. These results are confirmed by results of drillings at some other calderas. Then, caldera formation of both types is discussed: High-gravity-anomaly-type calderas are expected to originate from subsidence of high-density ejecta into the summit magma reservoir. On the calderas of this type, the genetic eruptions believed to be accompanied by subsidences were not actually observed, and consequently three examples are mentioned only briefly. The low-gravity-anomaly-type calderas are discussed from standpoint of both the models of collapses and explosions. It is also emphasized that dynamic pressure ofexplosions is an important factor in the caldera formation, not only volume of the ejecta. To confirm the possibility that volcanic ejecta and edifices collapse into magma reservoirs, we discuss stress propagation from a depleted reservoir upward towards the Earth surface. Formation mechanisms of large calderas of this type are speculated; large calderas measuring about 20 km across may develop by successive merging of component calderas over a long period of times. A Kamchatka caldera under enlargement during the Holocene period is interpreted by successive merging of five component calderas.

  6. Upper airway collapsibility is associated with obesity and hyoid position.

    Science.gov (United States)

    Genta, Pedro R; Schorr, Fabiola; Eckert, Danny J; Gebrim, Eloisa; Kayamori, Fabiane; Moriya, Henrique T; Malhotra, Atul; Lorenzi-Filho, Geraldo

    2014-10-01

    Upper airway anatomy plays a major role in obstructive sleep apnea (OSA) pathogenesis. An inferiorly displaced hyoid as measured by the mandibular plane to hyoid distance (MPH) has been consistently associated with OSA. The hyoid is also a common landmark for pharyngeal length, upper airway volume, and tongue base. Tongue dimensions, pharyngeal length, and obesity are associated with OSA severity, although the link between these anatomical variables and pharyngeal collapsibility is less well known. We hypothesized that obesity as measured by body mass index (BMI), neck and waist circumferences, and variables associated with hyoid position (pharyngeal length, upper airway volume, and tongue dimensions) would be associated with passive pharyngeal critical closing pressure (Pcrit). Cross-sectional. Academic hospital. 34 Japanese-Brazilian males age 21 to 70 y. N/A. We performed computed tomography scans of the upper airway, overnight polysomnography, and Pcrit measurements in all subjects. On average, subjects were overweight (BMI = 28 ± 4 kg/m(2)) and OSA was moderately severe (apnea-hypopnea index = 29 [13-51], range 1-90 events/h). Factor analysis identified two factors among the studied variables: obesity (extracted from BMI, neck and waist circumferences) and hyoid position (MPH, pharyngeal length, tongue length, tongue volume, and upper airway volume). Both obesity and hyoid position correlated with Pcrit (r = 0.470 and 0.630, respectively) (P obesity and hyoid position. Tongue dimensions, pharyngeal length, and the mandibular plane to hyoid distance are associated with obesity variables. These findings provide novel insight into the potential factors mediating upper airway collapse in obstructive sleep apnea. © 2014 Associated Professional Sleep Societies, LLC.

  7. Higher order concentration moments collapse in the expected mass fraction (EMF) based risk assessment

    Science.gov (United States)

    Srzic, Veljko; Gotovac, Hrvoje; Cvetkovic, Vladimir; Andricevic, Roko

    2014-05-01

    In this work Langrangian framework is used for conservative tracer transport simulations through 2-D extremely heterogeneous porous media. Conducted numerical simulations enable large sets of concentration values in both spatial and temporal domains. In addition to the advection, which acts on all scales, an additional mechanism considered is local scale dispersion (LSD), accounting for both mechanical dispersion and molecular diffusion. The ratio between these two mechanisms is quantified by the Peclet (Pe) number. In its base, the work gives answers to concentration scalar features when influenced by: i) different log-conductivity variance; ii) log-conductivity structures defined by the same global variogram but with different log conductivity patterns correlated; and iii) for a wide range of Peclet values. Results conducted by Monte Carlo analysis show a complex interplay between the aforementioned parameters, indicating the influence of aquifer properties to temporal LSD evolution. A remarkable collapse of higher order to second-order concentration moments [Yee, 2009] leads to the conclusion that only two concentration moments are required for an accurate description of concentration fluctuations. This explicitly holds for the pure advection case, while in the case of LSD presence the moment deriving function(MDF) is involved to ensure the moment collapse validity. An inspection of the Beta distribution leads to the conclusion that the two-parametric distribution can be used for concentration fluctuation characterization even in cases of high aquifer heterogeneity and/or for different log-conductivity structures, independent of the sampling volume used. Furthermore, the expected mass fraction (EMF) [Heagy & Sullivan, 1996] concept is applied in groundwater transport. In its origin, EMF is function of the concentration but with lower number of realizations needed for its determination, compared to the one point PDF. From practical point of view, EMF excludes

  8. In vitro susceptibility testing of Dientamoeba fragilis.

    Science.gov (United States)

    Nagata, N; Marriott, D; Harkness, J; Ellis, J T; Stark, D

    2012-01-01

    Dientamoeba fragilis is a commonly encountered trichomonad which has been implicated as a cause of gastrointestinal disease in humans. Despite the frequency of reports recording infections with this parasite, little research has been undertaken in terms of antimicrobial susceptibility. The aim of this study was to evaluate the susceptibility of D. fragilis to several commonly used antiparasitic agents: diloxanide furoate, furazolidone, iodoquinol, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, ronidazole, tetracycline, and tinidazole. Antibiotic susceptibility testing was performed on four clinical strains of D. fragilis, designated A, E, M, and V, respectively. Molecular testing followed, and all strains were determined to be genotype 1. The activities of antiprotozoal compounds at concentrations ranging from 2 μg/ml to 500 μg/ml were determined via cell counts of D. fragilis trophozoites grown in dixenic culture. Minimum lethal concentrations (MLCs) were as follows: ornidazole, 8 to 16 μg/ml; ronidazole, 8 to 16 μg/ml; tinidazole, 31 μg/ml; metronidazole, 31 μg/ml; secnidazole, 31 to 63 μg/ml; nitazoxanide, 63 μg/ml; tetracycline, 250 μg/ml; furazolidone, 250 to 500 μg/ml; iodoquinol, 500 μg/ml; paromomycin, 500 μg/ml; and diloxanide furoate, >500 μg/ml. This is the first study to report the profiles of susceptibility to a wide range of commonly used treatments for clinical isolates of D. fragilis. Our study indicated 5-nitroimidazole derivatives to be the most active compounds in vitro against D. fragilis.

  9. Efficacy of phosphatidylcholine in the modulation of motion sickness susceptibility

    Science.gov (United States)

    Kohl, R. L.; Ryan, P.; Homick, J. L.

    1985-01-01

    This study evaluated the efficacy of pharmacological doses of phosphatidylcholine (lecithin) in the modulation of motion sickness induced by exposure to coriolis stimulation in a rotating chair. Subjects received daily dietary supplements of 25 grams of lecithin (90 percent phosphatidylcholine) and were tested for their susceptibility to motion sickness after 4 h, 2 d, and 21 d. A small but statistically significant increase in susceptibility (+15 percent) was noted 4 h after supplemental phosphatidylcholine, with four of nine subjects demonstrating a marked increase in susceptibility. This finding was attributed to choline's stimulatory action on cholinergic systems, an action which opposes that of the classical antimotion sickness drug scopolamine. Chronic lecithin loading revealed a trend towards reduced susceptibility, possibly indicating the occurrence of adaptive mechanisms such as receptor down-regulation. Withdrawal from lecithin loading, perhaps coupled with anticholinergic treatment, might prove to be a potent prophylactic regimen and ought to be tested.

  10. Aquifer susceptibility in Virginia, 1998-2000

    Science.gov (United States)

    Nelms, David L.; Harlow, George E.; Plummer, L. Niel; Busenberg, Eurybiades

    2003-01-01

    The U.S. Geological Survey (USGS), in cooperation with the Virginia Department of Health, sampled water from 171 wells and springs across the Commonwealth of Virginia between 1998 and 2000 as part of the Virginia Aquifer Susceptibility study. Most of the sites sampled are public water supplies that are part of the comprehensive Source Water Assessment Program for the Commonwealth. The fundamental premise of the study was that the identification of young waters (less than 50 years) by multiple environmental tracers could be used as a guide for classifying aquifers in terms of susceptibility to contamination from near-surface sources. Environmental tracers, including chlorofluorocarbons (CFCs), sulfur hexafluoride (SF6), tritium (3H), and tritium/helium-3 (3H/3He), and carbon isotopes (14C and d13C) were used to determine the age of water discharging from wells and springs. Concentrations of CFCs greater than 5 picograms per kilogram and 3H concentrations greater than 0.6 tritium unit were used as thresholds to indicate that parts of the aquifer sampled have a component of young water and are, therefore, susceptible to near-surface contamination. Concentrations of CFCs exceeded the susceptibility threshold in 22 percent of the wells and in one spring sampled in the Coastal Plain regional aquifer systems. About 74 percent of the samples from wells with the top of the first water zone less than 100 feet below land surface exceeded the threshold values, and water supplies developed in the upper 100 feet of the Coastal Plain are considered to be susceptible to contamination from near-surface sources. The maximum depth to the top of the screened interval for wells that contained CFCs was less than 150 feet. Wells completed in the deep confined aquifers in the Coastal Plain generally contain water older than 1,000 years, as indicated by carbon-14 dating, and are not considered to be susceptible to contamination under natural conditions. All of the water samples from wells

  11. Regional, Local, and In-mine Moment Tensors for the 2013 Rudna Mine collapse

    Science.gov (United States)

    Whidden, K. M.; Rudzinski, L.; Lizurek, G.; Pankow, K. L.

    2013-12-01

    and time windows of 5 seconds, including P and S waves, also indicates an implosion source. However, a moment tensor calculated using an in-mine network of 26 short-period vertical seismometers with distances from 100 m to 8 km and first amplitude strategy to moment tensor solution, indicates a predominantly double-couple mechanism. Careful selection of time windows and moment tensor inversion method may be necessary to capture the full source for discrimination between tectonic and non-double-couple sources. Finally we compare the Rudna collapse to two other room-and-pillar mine collapses in the western United States. Their sources are similar although there are clear differences in Love wave amplitudes. Future work will investigate the relationship between seismic source, velocity structure, and shear wave generation for isotropic sources.

  12. Colony Collapse Disorder (CCD) and bee age impact honey bee pathophysiology.

    Science.gov (United States)

    vanEngelsdorp, Dennis; Traynor, Kirsten S; Andree, Michael; Lichtenberg, Elinor M; Chen, Yanping; Saegerman, Claude; Cox-Foster, Diana L

    2017-01-01

    Honey bee (Apis mellifera) colonies continue to experience high annual losses that remain poorly explained. Numerous interacting factors have been linked to colony declines. Understanding the pathways linking pathophysiology with symptoms is an important step in understanding the mechanisms of disease. In this study we examined the specific pathologies associated with honey bees collected from colonies suffering from Colony Collapse Disorder (CCD) and compared these with bees collected from apparently healthy colonies. We identified a set of pathological physical characteristics that occurred at different rates in CCD diagnosed colonies prior to their collapse: rectum distension, Malpighian tubule iridescence, fecal matter consistency, rectal enteroliths (hard concretions), and venom sac color. The multiple differences in rectum symptomology in bees from CCD apiaries and colonies suggest effected bees had trouble regulating water. To ensure that pathologies we found associated with CCD were indeed pathologies and not due to normal changes in physical appearances that occur as an adult bee ages (CCD colonies are assumed to be composed mostly of young bees), we documented the changes in bees of different ages taken from healthy colonies. We found that young bees had much greater incidences of white nodules than older cohorts. Prevalent in newly-emerged bees, these white nodules or cellular encapsulations indicate an active immune response. Comparing the two sets of characteristics, we determined a subset of pathologies that reliably predict CCD status rather than bee age (fecal matter consistency, rectal distension size, rectal enteroliths and Malpighian tubule iridescence) and that may serve as biomarkers for colony health. In addition, these pathologies suggest that CCD bees are experiencing disrupted excretory physiology. Our identification of these symptoms is an important first step in understanding the physiological pathways that underlie CCD and factors

  13. Colony Collapse Disorder (CCD) and bee age impact honey bee pathophysiology

    Science.gov (United States)

    Traynor, Kirsten S.; Andree, Michael; Lichtenberg, Elinor M.; Chen, Yanping; Saegerman, Claude; Cox-Foster, Diana L.

    2017-01-01

    Honey bee (Apis mellifera) colonies continue to experience high annual losses that remain poorly explained. Numerous interacting factors have been linked to colony declines. Understanding the pathways linking pathophysiology with symptoms is an important step in understanding the mechanisms of disease. In this study we examined the specific pathologies associated with honey bees collected from colonies suffering from Colony Collapse Disorder (CCD) and compared these with bees collected from apparently healthy colonies. We identified a set of pathological physical characteristics that occurred at different rates in CCD diagnosed colonies prior to their collapse: rectum distension, Malpighian tubule iridescence, fecal matter consistency, rectal enteroliths (hard concretions), and venom sac color. The multiple differences in rectum symptomology in bees from CCD apiaries and colonies suggest effected bees had trouble regulating water. To ensure that pathologies we found associated with CCD were indeed pathologies and not due to normal changes in physical appearances that occur as an adult bee ages (CCD colonies are assumed to be composed mostly of young bees), we documented the changes in bees of different ages taken from healthy colonies. We found that young bees had much greater incidences of white nodules than older cohorts. Prevalent in newly-emerged bees, these white nodules or cellular encapsulations indicate an active immune response. Comparing the two sets of characteristics, we determined a subset of pathologies that reliably predict CCD status rather than bee age (fecal matter consistency, rectal distension size, rectal enteroliths and Malpighian tubule iridescence) and that may serve as biomarkers for colony health. In addition, these pathologies suggest that CCD bees are experiencing disrupted excretory physiology. Our identification of these symptoms is an important first step in understanding the physiological pathways that underlie CCD and factors

  14. Colony Collapse Disorder (CCD and bee age impact honey bee pathophysiology.

    Directory of Open Access Journals (Sweden)

    Dennis vanEngelsdorp

    Full Text Available Honey bee (Apis mellifera colonies continue to experience high annual losses that remain poorly explained. Numerous interacting factors have been linked to colony declines. Understanding the pathways linking pathophysiology with symptoms is an important step in understanding the mechanisms of disease. In this study we examined the specific pathologies associated with honey bees collected from colonies suffering from Colony Collapse Disorder (CCD and compared these with bees collected from apparently healthy colonies. We identified a set of pathological physical characteristics that occurred at different rates in CCD diagnosed colonies prior to their collapse: rectum distension, Malpighian tubule iridescence, fecal matter consistency, rectal enteroliths (hard concretions, and venom sac color. The multiple differences in rectum symptomology in bees from CCD apiaries and colonies suggest effected bees had trouble regulating water. To ensure that pathologies we found associated with CCD were indeed pathologies and not due to normal changes in physical appearances that occur as an adult bee ages (CCD colonies are assumed to be composed mostly of young bees, we documented the changes in bees of different ages taken from healthy colonies. We found that young bees had much greater incidences of white nodules than older cohorts. Prevalent in newly-emerged bees, these white nodules or cellular encapsulations indicate an active immune response. Comparing the two sets of characteristics, we determined a subset of pathologies that reliably predict CCD status rather than bee age (fecal matter consistency, rectal distension size, rectal enteroliths and Malpighian tubule iridescence and that may serve as biomarkers for colony health. In addition, these pathologies suggest that CCD bees are experiencing disrupted excretory physiology. Our identification of these symptoms is an important first step in understanding the physiological pathways that underlie CCD and

  15. Facies-controlled fluid migration patterns and subsequent reservoir collapse by depressurization - the Entrada Sandstone, Utah

    Science.gov (United States)

    Sundal, A.; Skurtveit, E.; Midtkandal, I.; Hope, I.; Larsen, E.; Kristensen, R. S.; Braathen, A.

    2016-12-01

    The thick and laterally extensive Middle Jurassic Entrada Sandstone forms a regionally significant reservoir both in the subsurface and as outcrops in Utah. Individual layers of fluvial sandstone within otherwise fine-grained aeolian dunes and silty inter-dune deposits of the Entrada Earthy Member are of particular interest as CO2 reservoir analogs to study injectivity, reservoir-caprock interaction and bypass systems. Detailed mapping of facies and deformation structures, including petrographic studies and core plug tests, show significant rock property contrasts between layers of different sedimentary facies. Beds representing fluvial facies appear as white, medium-grained, well-sorted and cross-stratified sandstone, displaying high porosity, high micro-scale permeability, low tensile strength, and low seismic velocity. Subsequent to deposition, these beds were structurally deformed and contain a dense network of deformation bands, especially in proximity to faults and injectites. Over- and underlying low-permeability layers of inter-dune aeolian facies contain none or few deformation bands, display significantly higher rock strengths and high seismic velocities compared to the fluvial inter-beds. Permeable units between low-permeability layers are prone to become over-pressured during burial, and the establishment of fluid escape routes during regional tectonic events may have caused depressurization and selective collapse of weak layers. Through-cutting, vertical sand pipes display large clasts of stratified sandstone suspended in remobilized sand matrix, and may have served as permeable fluid conduits and pressure vents before becoming preferentially cemented and plugged. Bleached zones around faults and fractures throughout the succession indicate leakage and migration of reducing fluids. The fluvial beds are porous and would appear in wireline logs and seismic profiles as excellent reservoirs; whereas due to dense populations of deformation bands they may in

  16. Sonographic evaluation of intravascular volume status: Can internal jugular or femoral vein collapsibility be used in the absence of IVC visualization?

    Directory of Open Access Journals (Sweden)

    Alistair Kent

    2015-01-01

    Full Text Available Introduction: Inferior vena cava collapsibility index (IVC-CI has been shown to correlate with both clinical and invasive assessment of intravascular volume status, but has important limitations such as the requirement for advanced sonographic skills, the degree of difficulty in obtaining those skills, and often challenging visualization of the IVC in the postoperative patient. The current study aims to explore the potential for using femoral (FV or internal jugular (IJV vein collapsibility as alternative sonographic options in the absence of adequate IVC visualization. Methods: A prospective, observational study comparing IVC-CI and Fem- and/or IJV-CI was performed in two intensive care units (ICU between January 2012 and April 2014. Concurrent M-mode measurements of IVC-CI and FV- and/or IJV-CI were collected during each sonographic session. Measurements of IVC were obtained using standard technique. IJV-CI and FV-CI were measured using high-frequency, linear array ultrasound probe placed in the corresponding anatomic areas. Paired data were analyzed using coefficient of correlation/determination and Bland-Altman determination of measurement bias. Results: We performed paired ultrasound examination of IVC-IJV (n = 39 and IVC-FV (n = 22, in 40 patients (mean age 54.1; 40% women. Both FV-CI and IJV-CI scans took less time to complete than IVC-CI scans (both, P < 0.02. Correlations between IVC-CI/FV-CI (R 2 = 0.41 and IVC-CI/IJV-CI (R 2 = 0.38 were weak. There was a mean -3.5% measurement bias between IVC-CI and IJV-CI, with trend toward overestimation for IJV-CI with increasing collapsibility. In contrast, FV-CI underestimated collapsibility by approximately 3.8% across the measured collapsibility range. Conclusion: Despite small measurement biases, correlations between IVC-CI and FV-/IJV-CI are weak. These results indicate that IJ-CI and FV-CI should not be used as a primary intravascular volume assessment tool for clinical decision support in

  17. Inherited susceptibility and radiation exposure

    Energy Technology Data Exchange (ETDEWEB)

    Little, J.B. [Harvard School of Public Health, Boston, MA (United States)

    1997-03-01

    There is continuing concern that some people in the general population may have genetic makeups that place them at particularly high risk for radiation-induced cancer. The existence of such a susceptible subpopulation would have obvious implications for the estimation of risks of radiation exposure. Although it has been long known that familial aggregations of cancer do sometimes occur, recent evidence suggests that a general genetic predisposition to cancer does not exist; most cancers occur sporadically. On the other hand, nearly 10% of the known Mendelian genetic disorders are associated with cancer. A number of these involve a familial predisposition to cancer, and some are characterized by an enhanced susceptibility to the induction of cancer by various physical and chemical carcinogens, including ionizing radiation. Such increased susceptibility will depend on several factors including the frequency of the susceptibility gene in the population and its penetrance, the strength of the predisposition, and the degree to which the cancer incidence in susceptible individuals may be increased by the carcinogen. It is now known that these cancer-predisposing genes may be responsible not only for rare familial cancer syndromes, but also for a proportion of the common cancers. Although the currently known disorders can account for only a small fraction of all cancers, they serve as models for genetic predisposition to carcinogen-induced cancer in the general population. In the present report, the author describes current knowledge of those specific disorders that are associated with an enhanced predisposition to radiation-induced cancer, and discusses how this knowledge may bear on the susceptibility to radiation-induced cancer in the general population and estimates of the risk of radiation exposure.

  18. Influence of Oil on the Magnitude and Rate of Collapsible Soils ...

    African Journals Online (AJOL)

    Collapsible soils particularly cover arid and semi arid regions where sometimes petroleum industry is well developed. The hydrocarbon is transported by pipelines towards refineries located in coastal areas. In case of a leak, these soils may collapse. The experimental work, carried out in oedometer illustrates the influence ...

  19. Non-adiabatic radiative collapse of a relativistic star under different ...

    Indian Academy of Sciences (India)

    We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star filled with a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid ...

  20. Micro-mechanism of vapor film collapse on high temperature particle surface

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Yutaka; Tochio, Daisuke [Dept. of Mechanical Systems Engineering, Yamagata Univ., Yonezawa, Yamagata (Japan)

    1999-07-01

    Thermal detonation model is proposed to describe vapor explosion. According to this model, vapor film on pre-mixed high temperature droplet surface is needed to be collapsed for the trigger of the vapor explosion. It is pointed out that the vapor film collapse behavior is significantly affected by the subcooling of low temperature liquid. However, the effect of subcooling on micro-mechanism of vapor film collapse behavior is not experimentally well identified. The objective of the present research is to experimentally investigate the effect of subcooling on micro-mechanism of film boiling collapse behavior. As the results, it is experimentally clarified that the vapor film collapse behavior in low subcool condition is qualitatively different from the vapor film collapse behavior in high subcooling condition. In high subcooling condition, instability of the vapor film dominates the vapor film collapse on the particle surface. On the other hand, micro-mechanism at the interface between vapor and liquid such as micro-jet is dominant in low subcool condition in case of vapor film collapse by pressure pulse. (author)